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Full text of "Paley's Natural theology, with illustrative notes"

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2.l,hL 



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PALEY'S 
NATURAL THEOLOGY, 



WITtt 



ILLUSTRATIVE NOTES. 



HENRY LORD JtBOUGHAM, F.R.S. 

AMD MXMBEB OF THE NATIOMAI. IWtTITUTX OF FSAVOB, 



SIR CHARLES BELL, K.G.H., F.R.S., L. & E. 

PBOFXSSOB or 8UBOKBT IN THK UKIVKBSITT OF BDIMBUBOH, FOBMBBLT 

OF TBB OOUMCII., AMD PBOF. AMAT. BOY. COLL. SXJBO. LOMDOM, , 

XTO. XTO. 



TO WHICH ARB ADDBO 

SUPPLEMENTARY DISSERTATIONS, 

Bt sir CHARLES BELL. 
iiriTH NUMEROUS WOOD-CUTS, 

TWO VOLS. VOL. I. 



LONDON: 
CHARLES KNIGHT, LUDGATE STREET. 

MDCCCXZZVI. 

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LONDON: 

PrHtIrd by W. CLowEivniid Sons 

St:unford Street. 



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ADVERTISEMENT. 



It is apparent that considerable difficulty must 
attend the task of illustrating the justly cele- 
brated work of Dr. Paley. According to hk 
design, no one subject could be folly and fittally 
treated : the eye, the ear, the teeth, and many 
other organs, are of necessity touched upon oc* 
casionally and repeatedly in different chapters, 
at one time to prove prospective eontrivances, 
at another to show compensation, or relation* 
This is undoubtedly a plan suited to the otqect 
of the author; and ttifie and the opinion of tl^ 
public pronounced <m the work have amply cent 
firmed his judgment in adopting it Fearfol of 
introducing too many additional subjects- in the 
notes to the text, and thus overloading the ar* 
gument, we have thrown the Dissertatkms, in 
illustration of the various matters, into an Ap- 
pendix : thus leaving the reader more at liberty 
to select the subjects on which he desires further 
information. 

Mr. Paxton, of Oxford, several years ago, pub- 
lished a valuable work illustrating the " Natural 

b2 



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IV ADVERTISEMENT. 

Theology'' to which the reader is referred for 
fiirther illustration on some of the subjects, par- 
ticularly those connected with anatomy. 

The authors of the present work have been 
indebted to Professor Lindley, of the London 
University, for the botanical notes to the twen- 
tieth chapter ; and to Mr. Waterhouse, Curator 
of the Zoological Museum of London, for the 
entomological notes to the nineteenth chapter; 
those which were kindly communicated by Bishop 
Brinkley are specified in chapters twenty-two and 
twenty-five. 

The Dissertations connected with the last ten 
chapters will form a fourth volume, which will 
complete this work. 

The whole of the Notes, and nearly the whole 
of the Dissertation, now published, to the first 
seventeen chapters, were prepared for the press 
several months ago, and the greater part of them 
printed last summer. But the expediency of 
making some additions to the Dissertations has 
occasioned the publication to be delayed. 



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CONTENTS OF VOL. I. 



CHAPTER I. 

8TATB OF THK ARGUHENT. ^ >. 

Waich, page 2 ; eight cases, 4-10. 

jyoie I, Referring to the Appendix for a description of the me^ 
chanism of the watch, page 1 ; 2, on '< how the stone came 
to be there," 1 ; 3, on the turning of 0¥al frames, 5 ; 4, on 
"laws '* of nature, &c., 9. 

CHAPTER II. 

STATE OF THE ARGUHEMT CONTINUED. 

Aofe 5, OB the management and tendency of the argument ia 
Chapter II., 19. 

CHAPTER III. 

APPLICATION OF THE ARGUMENT. , 

Eye and telescope, 22; light — distance, 31 j'^eyes of birds, 3G; 
eyes of fish, 37; minuteness of picture^ 41; socket— eye. 
brow<.-eye-lid— tears, 42; nictitating membrane-^muscle, 
44 ; expedients, 48 ; why means used, 50 ; ear, 52. 

N'oie 6y referring to Appendix, 21 ; 7, referring to Appendix, and 
on the adaptation of the eyes of fish to the medium in which 
they live, 23 ; 8, referring to Appendix, and on refraction, 
27 i 9, on the adjustment of the eye to different distances. 



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Yl CONTENTS. 

33 ; 10, on the pressure of the sea at great depths, and on 
the structure of the eyes of fishes in order to resist that 
pressure, 39 ; 11, referring to the Appendix for observations 
on the structure of the eyes of fishes, 44 ; 12, on the man- 
brana mctitanif 47 ; 13, referring to Appendix for observations 
on the limits whidi the Deity «eeois to have prescribed to 
his own power, 50 ; 14, referring to the Appendix, and on 
the structure of the ear, 52 ; 15, on the chain of bones in 
the ear, 57. 

CHAPTER IV. 

OP TBB SUCCESSION OF PLANTS AND ANIMALS. 

No account hereby of contrivance, 63; plants, ti^. ; oviparous 
animals, 64; viviparous — rational animak, 66; instance 
from Gardener, 67. 

Note 16, on the limits of the term of existence, and on reproduc- 
tion, 68. 

CHAPTER V. 

APPUCATION OP THE AKGUMBNT CONTINUID. 

i epetition from Chapter I., 72; imperfection, ib.; superfluous 
parts, 74 ; atheistic argument, 77 ; remains of x>0S8ible formSy 
82 ; use arising out of the parts, 86 ; a principle of order, 91 ; 
of our ignorance, 92. 
Note 17, on the suspension of respiration, 74; 18, on parts of 
animals said to he superfluous, 76 ; 19, on results supposed 
to arise from chancy, 80 ; 20, on the supposition of animals 
having been produced by chance, 84; 21, on the dexterity 
which man acquires by practice as distinguishing him from 
other animals, 89. 

CHAPTER VI. 

THE ARGUHBNT CUMULATIVE. 



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0OKT£Nr6« Vti 

-CSAPTILR VII* 
fnm MBDiainoii. AnD^mMEomiMUsAL pjsm amo vuNorioift op 

ANIKALt AND VEOSTABI.XS. 

If ifcUium of iowwledgt &• pro«f of want of contnrance, 99 ; 
<m'CihemiBhy, 105 ; seontion, 107» 

K9te t2f on the perfection of the mnnechanical parts of animals, 
^ ; 23, on the gastric jidee as not acting npon the stomach 
of the living animal, 107. 

CHAPTER VIII. 

MECHANICAL ARBANOXMXNT IN THE HUMAN PRAMB. 

Of bones, 116; neck, tft.; fore-arm, 119; spine, 123; chest, 133; 
knee-pan, 134 ; shoulder-blade, 136 ; joints, 137 ; ball and 
socket, 139; gynglymus, 141; knee, 142; ankle, ib.; 
shoulder, 143 ; passage of blood-vessels, 145 ; gristle, 146 ; 
moveable cartilages, 148 ; synovia, 150 ; how well the joints 
wear, 151 ; immoveable joints, 152. 

Note 2Af on the meaning of the terms tenon aad mortice, 118; 
26, on variations of structure to suit the peculiar condition 
or necessities of di£ferent animab, 130; 27, ie£Brring to 
Afigeadix tor further proofs of adaptation of structure to 
habits and condition of animals, 134; 28, on the shoulder- 
blade and collar-bone, 136 ; 29, on the absence, in the oran- 
outang, of the ligament in the head of the thigh-bone, 141 ; 
30, on the ankle-joint, 143; 31, on the cartilage which 
covers the ends of the bones, 147 ; 32, on the manner in 
which the thigh-bone rests upon the shin-bone, and the use 
of the cartilage between them, 149 ; 33, on absorption, in a 
case of inflammation of a joint, 1 5 1. 

CHAPTER IX. 

OF THE MDSCLB6. 

Suitableness to the joints, 154 ; antagonist nraseles, 15B ; not ob- 
structing one another, 159 ; action wanted where Uieir 



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Tltt COKTENTS. 

utoation wocdd be inconvenient, 160 ; Tariety of figure, 161 ; 
. how many thingt must be right for health, 163; variety, 
quickness, and precision of muscular motion, 165 ; tongue, 
ib,; mouth, 166; nose, 169; music^writinj, 171; iphloo- . 
ters, 172; combination of muscles, ]73; delicacy of small 
muscles, 174; mechanical disadvantages, ib.; single 
muscles, 176; lower jaw, ib,; slit tendons, 178; bandago 
at the ankles, ib. ; hypothesis from appetency repelled, 179 ; 
Keiirs enumeration of muscles, 180 ; why mechanism is not 
more striking, 181; description inferior to inspection, i6. ; 
quotation from Steno, 182. 

Note 34, on the balance of action between the antagonist muscles, 
157 ; 35, on the sacrifice of power in certain muscles, in order 
to acquire velocity, 163; 36, on the complexity of structure 
in the tongue, 170. 

CHAPTER X, 

OF TBB VB8SBL8 OF AMIMAL BODIES. 

i. The circulation of the blood, 184 ; disposition of the blood- 
vessels, 185 ; arteries and veins, 186 ; il heart, as receiving 
and returning the blood, 188; heart, as referable to the 
lungs, 191 ; valves of the heart, 199; vital motions invo- 
luntary, 205 ; pericardium, ib, ; iii. alimentary system, 
207 ; passage of the food through the stomach to the intes- 
tines, ib,; passage of the chyle through the ladeals and 
thoracic duct to the blood, 208 ; length of intestioes, 209 ; 
peristaltic motion, 210 ; tenuity of the lacteals, ib. ; valves 
of the thoracic duct, 211 ; entrance at the neck, ib, ; diges- 
tion, 212; iv. gall bladder, 216 ; oblique insertion of the 
biliary duct into the intestines, 217 ; v. parotid gland, 218 ; 
VL larynx, 219; trachea— gullet — epiglottis, 219,220; rings 
of the trachea, 2^1 ; sensibility, 222 ; musical instrument, 
224; lifting the hand to jkhe head, 225. 

Note 37, referring to the Appendix for a dissertation on the circu 



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CONTENTS* IX 

lation of the blood and its uf^V 185j 38, on the compoiition 
of the atmosphere, 191 ; 39, on the necessity of exposing 
thjB venous blood to the air, 192 ; 40, on the valves of tho 
veins and arteries, 201 ; 41, on the germination of seeds 
which have passed unbroken through the stomachs of animals, 
214 ; 42, referring to Appendix on the stomach of the,borse, 
217; 43, on the necessity of certain sensibilities in the 
body, 223 ; 44, referring to Appendix for observations on the 
luugs, 225. 

CHAPTER XI. 

OF THE ANIMAL STRUCTURE RSOAROBD AS A MASS. 

u Correspondence of sides, 228; not belonging to the peparate 
,Umbs,,230j nor to the intemalj;coatents, 231; not to the 
feeding vessels, 232 ; ii« package, 233 ; heart, 2^5 ; lungs, 
ib, ; liver, ib. ; bladder, 236 ; kidneys, ib, ; pancreas, t6. ; 
spleen, ib, ; omentum, 237 ; septa of the brain, 23b ; guts, t6. ; 
iiL beauty, 240 ; in animals, 241 ; in flowers, 242 ; whether 
any natural sense of beauty, 243; iv. concealment, 245; 
V. standing, 246 ; vi. interrupted analogies, 230 ; periosteum 
at the teeth, 251 ; early skin at the nails, 252 ; soft integu- 
ments at the skull, 253. 

Note 45, on the spleen, 237 ; 46, on the sensibility by which we 
are enabled to balance the body, 249 ; 47, referring to the 
Appendix for a dissertation on the teeth, 250 ; 48, on the 
use of the nails of the fingers, 2^2 ; 49, referring to the 
Appendix for a note ou the form of the skull, 253. 

CHAPTER XII. 

COMPARATIVE ANATOMY. 

i. Covering of animaU, 257 ; of man, ib. ; of birds, 258 ; struc 
ture of feathers, 260 ; black down, 264 ; ii. mouths of 
animals, 265; bills of birds, 267; serrated biUs, 270; 
affinity of mouths, 273; iii. gullets of animals, 274; iv. 



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z coNTSirrs. 

iUtestfaieB of amiMliy 875 ; -nbnm or pIMM, tft. ; lengtlt^ 
S76 ; T. bonet of animals, 277; bonet of bnds> 16. ; vi lungs 
of animals, 278 ; hmgs of birds, ib. ; vfu birds ovipanras, t6. ; 
▼iiL instrmnetrti of motion, 279; ^irings of birds, »6.; fins of 
fUh, 282; ireb-feet^rf water-fowl, 287 ; ix. oenses oi ani- 
mals, 288. 

Note 50, on the coverings of birds and other animals with refer- 
ence to warmth, 264 ; 51, on the adaptation of the bills of 
birds to the habits of each kind, 268 ; 52, on the connexion 
of the fifth nerve of the brain with the organ of touch, 272 ; 
53, referring to the Appendix for observations on the rela- 
tion of the bodies of birds to the atmosphere, 27^ ; 54, on 
tl» neeetsitj of birds being oviparous in order to setain the 
'power of flying, 279 ; 5S, on the sin^larity of the eyvtem of 
bones in all vertebrated aninsato, 282 ; 56, on the uses and 
fliiweolar power of the fins of fishes, 285. 

CHAPTER XIIL 

PBOUUAR OBQANIZATIOirS. 

Pax-wax of quadrupeds, 292 ; oil of birds, 293 ; aiivbladder of 
fish, 294 ; fang of viper, 297 ; bag of opossum, 298 ; claw 
of heron, 299; stomach of camel, 300; tongue of wood- 
pecker, 301; babyroossa, 306. 

Note 57, OD the ligaments of the neck, 292 ; 58, on the air-bladder 
of fishes, 296 ; 59, on the habits and tongue of the wood- 
pecker, 302 ; 60, on the erroneous notion of the babyroussa 
sleeping standing, 307. 

CHAPTER XIV. 

PROSPECTIVE CONTOIVANCES. 

Teeth, 308; milk, 311; eye of the fioetus, 314; lungs of the 
foBtue— Ibramen ovale, &c. &c., 315. 



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CONTBKT& ILk 

iit9ie^Ute£mmgioAp§nL6&K£at note iipoa tlie teatb, 310 ; 62, 
BU tht atinii by f^iek the aetaad set ot teeth uenyule to 
fliifMPii ^the Bmi, 311 ; &3» on the piovisioB for &e first 
nourishment of plants and animals, 312-; 63, on the gra- 
dual developoo^nt of animal bodies, 317. 

CHAPTER XV. 

RBLATI0M8. 

AlimentaTy system, 321; kidneys, ureters, and bladder, 325; 
eyes, hands, feet, 326; sexes, ib.; teats and mouths, 327; 
particular relations, ib.; swan, ik,; mole, 329. 

CHAPTER XVL 

COMPENSATION. 

Elephant's proboscis, 333 ; hook in the bat's wing, 336; crane^s 
neck, ib. ; panof s bill, 337 ; Rider's web, 338 ; multiplying^ 
eyes of insects, 341 ; eyelid of the cameleon, 342 ; intestines 
of the alopecias, 343 ; mail — muscle — cockle-^lobster, 344 ; 
sloth — sheep, 346 ; more general compensations, 347 ; want 
of fore>teeth — rumination, ib^ ; in birds, want of teeth and 
gisttid, 349 ; reptiles, 352. 

JVb/e 64, en the unreasonableness of the notion of a change in the 
. original structure of animal organs, 334 ; 65, interesting 
particulars concerning the powers and habits of spiders, 339 ; 
66-67, referring to Appendix, 346, 347 ; 68, on the di- 
gestive organs, with reference to the different kinds of food, 
348 ; 69, on the relation between the mouths and stomachs 
of animals, 351 ; 70, on the variety of the instruments of 
motion of different animals, 354. 

CHAPTER XVII. 

THE liUJknON OF ANIMATED BODIES TO INANIMATE NATURE. 

Wings of birds— fins of fish— air and water, 353 ; ear to the air, 



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Xn CONTENTS. 

ib, ; oigani of ipeec h vo ice aad reipinlioii.to air, 364$ eft 
to light, ib, ; nie of animaU to external thingiy 365 ; of tbe 
inhabitanta of the earth and aea to their elementay 360 ; 
sleep to xught, 361. 

Note 71, referring to the Appendix for obserrations on the bones 
of large aoimals, 360; 72, on the succession of day and 
night and on the changes of the seasons, with reference to 
the happiness of animals, 364. 

CHAPTER XVIII. 

INSTINCTS. 

Iiicabation of eggs, 369 ; deposition of eggs of imects, 376 ; solu- 
tion from sensations considered, 382. 

Note 73, on the unchaiigeableness of animal instincts, 369; 74, 
on the instinct of the chicken in breaking the shell of its 
egg, 372; 75, on the natural and instinctiTO feelings of 
man, 380 ; 76, on the arguments of sceptics, and on compen- 
sations in animal organs and powers, 385. 

CHAPTER XIX. 

OF INSECTS. 

Elytra of the scarabsBus, 393 ; borer of flies, 395 ; sting, 398 ; 
proboscis, 400 ; metamorphosis of insects, 404 ; care of 
eggs, 408 ; observations limited to particular species, 409 ^ 
thread of silk-worm and spider, ib. ; wax and honey of bee, 
412 ; sting of bee, 414 ; forceps of the panorpa tribe, 
1*6.; brushes of flies, 415; glow-worm, ib,; motion of the 
larva of the dragon-fly, 417; gossamer spider, 418; shell 
animals, 420 ; snail shells, ib, ; univalve shell-fish, 422 ; 
bivalve, 423 ; lobster shell, 424 ; variety of insects, 425. 

Note 77, on the antennae of insects, 392 ; 78, on the word 
coleoptera, 394 ; 79, on the wing-cases of braekefytra, tb, ; 
80, on the wing-cases of the genera moiorckut, ib, ; 81, on 



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CONTENTS. XIU 

the gratis Hitier^ 395 ; 82, on paratitical insecti, 396 ; 83, 
on the OYipositorf of insects, 397 ; 84, whimble of insects an 
ovipositor, ih, ; 85, stings of insects used as oripositors, 398 ; 

86, anatomical description of the proboscis of the bee, 400 ; 

87, on the indentation in the head to receive the proboscis, 
401 ; 88, on the parts of the mouths of insects, ib» ; 89^. 
referring to note 86; 90, on the habits of bees in collecting 
food, &C., 402 ; 91, description of the parts of the mouth of 
the common flea, 403 ; 92, on the structure of the mouths 
of caterpillars, 404; 93, on the di^rence between the larva 
and the perfect insect, 406 ; 94, on bees' wax, 413 ; 95, on 
the construction of the cells of bees, 414 ; 96, on the genus 
Trichiut, 414 ; 97, on the mode in which the stag-beetle 
cleans its antennae, 415 ; 98, on the glow-worm, 416 ; 99, on, 
the glow-worm's light, 417 ; 100, on the manner in which the 
spider attaches its thread to different bodies, 419 ; 101, on 
the number of the species of insects, 425 ; 102, number of 
Uie spedes of butterfly in this country, 426 ; 103, on insects 
subsisting on carrion, 428; 104, on the similarity between 
the improvements in paper-making and the construction of 
watp-paper; and on the migration of birds, 429. 

CHAPTER XX. 

OF PLANTS. 

Preservation, perfecting, and dispersing of seed, 431 ; germina- 
tion, 443 ; tendrils, 445 ; particular species, 448 ; vallis- 
neria, ib, ; Cuscuta Europsa, 449 ; misseltoe, 451 ; colchi- 
chum autumnale, ib, ; dionsa muscipula, 454. 

JVo/e 105, on the structure of birds, 435 ; 106, correction of the 
text, 447; 107, on the Cuscuta Europtea, 450 ; 108, on para- 
sitical plants, 451 ; 109, no attracting syrup on the leaves of 
the dionaea, 455 ; 110, description of the pitcher-plaut, ib» 



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ILLUSTRATIVE WOOD-CUTS.— VOL. I. 



1. Thb form of the eye, 22. 

2. Section of the anterior part of the hnman eye, to show the 

manner in which the images of objects are impressed upon 
the retina, 29. 

3. The iris separated from the eye, and laid out Hat, 3(y. 

4. Head of the eel, showing the form of the eye, 38. 

5. Flan of the human ear, 52. 

6. Bones of the ear, 55. 

7. Bones of the ear separated, 56. 

8. Drum of the ear, 59. 

9. The eye, showing the transmission of the images of ohjects, 

95* 

10. A muscle, 100. 

11. The lower surface, or base, of the stuU, 115. 

12. Uppermost vertebra, or atlas, 117. 

13. Articulation of the first and second fertebrs of the neck, 1 18. 

14. Section of the three lower vertebzs, 123. 

15. Three views of the knee-joints, 135. 

16. Muscle with tendons on different sides, 162. 

17. Figure showing how velocity is acquired by pulling ob- 

liquely, 163. 

18. Figure of the arm, showing the action of tlie biceps muscle, 

174. 

19. The heart and great blood-vessels, 183. 

20. The two sides of the heart separated, 194. 

21. Section of the ventricle and the artery, 197. 

22. Valve of the great artery, 203. 

23. Bones of the human foot, 248. 



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ILLUSTRATIVE WOOD-CUTS. XV 

24. Heads of birds, showing the form of the bills, 267. 

25. Head and neck of the heron, 269. 

26. Head of the spoon-bill, 271. 

27. Feet of birds, with and without web, 287. 

28. Heads of the wolf and hare, showing the different manner in 

which the ears are turned, 289. 

29. Iris of the lion's eye, 290. 

30. Di8.<tecfed head of the woodpecker, 304. 

31. Skull of the babyroussa, 307. 

32. Spider suspended from a twig, 338. 

33. Ovipositors of insects, 395. 

34. Proboscis of the bee dissec,ted, 400. 

35. Mouths of beetle and bees dissected, 405. 

36. Silkworm, 410. 

37. Garden snail, 420. 

38. Prickly oyster, 422. 

39. Ck)ck's-comb oyster, 422. 

40. Venus' heart cockle, 423. 

41. Poppy, 433. 

42. Cuscuta Europaea, 449. 

43. Autumnal crocus, 452. 

44. Pitcher-plant, 455. 



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NATURAL THEOLOGY. 



CHAPTER I. 

STATE OF THE ARGUMENT.* 

In crossing a heath, suppose I pitched my foot 
against a stone, and were asked how the stone 
came to be there, I might possibly answer, that, 
for anything I knew to the contrary, it had lain 
there for ever; nor would it, perhaps, be very 
easy to show the absurdity of this answer.* But 

* The last note of the Appendix describes the me- 
chanism of a watch, and illustrates the elementary prin- 
ciples of mechanics. Contrasted with the mere mechan- 
ism, there is another essay on the mechanism of the 
animal body. These may be perused either before or 
after reading the present chapter. 

• The argument is here put very natmrally. But a 
considerable change has taken place of late years in the 
knowledge attained even by common readers, and there 
are few who would be without reflection " how the stoUe 
came to be there." The changes which the earth's 
surface has undergone, and the preparation for its pre- 
sent condition, have become a subject of high interest ; 

B 



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2 NATURAL THEOLOGY. 

suppose I had found a watch upon the ground^ 

and there is hardly any one who now would, for an 
instant, believe that the stone was formed where it lay. 
On hfting it, he would find it rounded like gravel in a 
river : he would see that its asperities had been worn off, 
by being rolled from a distance in water : he would per- 
haps break it, look to its fracture, and survey the sur- 
rounding heights, to discover whence it had been broken 
off, or from what remote region it had been swept hither; 
he would consider the place where he stood, in reference 
to the level of the sea or the waters ; and, revolving all 
these things in his mind, he would be impressed with 
the conviction, that the surfoce of the earth had under- 
gone some vast revolution. 

Such natural reflections lead an inteUigent person to 
seek for information in the many beautiful and inte- 
resting works on geology that have been published in our 
country of late years. And by these he will be led to 
infer, that the fair scene before him, so happily adapted 
for the abode of man, was a condition of the earth re- 
sulting from many successive revolutions taking place at 
periods incalculably remote; and that the variety of 
mountaiu and valley, forest and fertile plain, promontory 
and shallow estuary, formed a world suited to his capa- 
cities and enterprise. 

• So true is the observation of Sir J. Herschel, ** that 
ihit situation of a pebble may afford him evidence of 
ibe state of die globe he inhabits myriads of ages ago, 
Wore his species became its denizens." 



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NATUKAL THEOLOGY*: 3 

and it should be ihquired how the watch happenedt 
to be in that place^ I should hardly think of the 
answer which I had before given— tJiat> for any- 
thing I knew, the watch might have always beei^ 
there. Yet why should not this answer serve fiwr 
Ae watch as well as for the stone ? why is it not 
as admissible in the sea>nd case as in the first? 
For this reason, and for no other, viz., that, when 
we come to inspect the watch, we perceive (what 
we could not discover in the stone) that its seve-^ 
ral parts are framed and put together for a pur- 
pose» €. g. that they are so formed and adjusted as 
to produce motion, and that motion so regulated 
as to point out the hour of the day ; that, if the^ 
different parts had been differently shaped from^ 
what they are, of a different size from what they 
are, or placed after any other manner, or in any 
other order than that in which they are placed, 
dither no motion at all would have been carried 
on in the machine, or none which would have an- 
swered the use that is now served by it. To 
reckon up a few of the plainest of these parts, and 
of their offices, all tending to one result. We see 
a cylindrical box containing a coiled elastic spring, 
which, by its endeavour to relax itself, turns round' 
the box. We next observe a fleidble chain (a^- • 
ficiaUy wrought for the sake of flexure) commum^ 
cf^ing tbe action of the spring from the box 'to 

b2 



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■j^.AAcJu.,1. ^ jmm^mm^man 



4 NATURAL THEOLOGY. 

the fusee. We then find a series of wheek, the 
teeth of which catch in, and apply to, each other, 
conducting the motion from the fusee to the balance, 
and from the balance to the pointer, and, at the 
same time, by the size and shape of those wheels, 
so regulating that motion as to terminate in caus- 
ing an index, by an equable and measured pro- 
gression, to pass over a given space in a given 
time. We take notice that the wheels are made 
of brass, in order to keep them from rust ; the 
springs of steel, no other metal being so elastic ; 
that over the face of the watch there is placed a 
glass, a material employed in no other part of the 
work, but in the room of which, if there had been 
any other than a transparent substance, the hour 
could not be seen without opening the case. This 
mechanism being observed (it requires indeed an 
examination of the instrument, and perhaps some 
previous knowledge of the subject, to perceive and 
understand it ; but being once, as we have said, 
observed and understood), the inference, we think, 
is inevitable, that the watch must have had a 
maker : that there must have existed, at some time, 
and at some place or other, an artificer or artificers 
who formed it for the purpose which we find it ac- 
tually to answer; who comprehended its construc- 
tion, and designed its use. 

I. Nor would it, I apprehend, weaken the con- 



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NATURAL THEOLOGY. 5 

elusion, that we had never seen a watch made; 
that we had never known an artist capable of 
making one ; that we were altogether incapable 
of executing such a piece of workmanship our- 
selves, or of understanding in what manner it was 
performed; all this being no more than what is 
true of some exquisite remains of ancient art, of 
some lost arts, and, to the generality of mankind, 
of the more curious productions of modem manu- 
^cture. Does one man in a million know how 
oval frames are turned'? Ignorance of this kind 

• It is certainly a thing not easily expressed in words* 
The nave of a circokr wheel mores on s nngleptTot; 
bat there are here two pivots, tnd grooves in the whed 
to cOTrespond with them. These two grooves cross esch 
<*ber, and pla j upon die pivoU in soch s numnor that 
the centre of motion varies, and the rim of the whed 
naoTcs in an diesis. It is exacdy on the same prin- 
cqile that we draw an oval figoie, by driving two nails 
mto ^iKnrd, and throwing a band round them, and then 
mi ning ^le pencil roond within the band* These two 
naOs are in tlie points caDcd by malhematicians the /bcl 
of tbe owal or dSiput; and according, a fandamental 
pim> c at5 of ^»e carve ia, diat die smn of any two Hnes 
whaftewcr, drava hmt tike two fod to any point in the 
carve, ia alwajad^aaMe. These poinU are calkd /oet% 
^res^ ^e c ■n ae hg^ rdhetei horn the sar^KC oC aa oval 
t uBCic aad pfodoces neat. 



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^ NATURAL THBOLOOY; 

^^aljts our opinioB of the unseen and unknown 
artistes skill, if be be unseen and unknown, but 
raises no doubt in our minds of the existence and 
.ag^cy of such an artist, at some farmer time, and 
in some place or other. Nor can I perceive that 
it varies at all the inference, whether the question 
arise concerning a human agent, or concerning an 
agent of a different species, or an agent possess- 
ing, in some respects, a different nature. 

II. Neither, secondly, wpuld it invalidate our 
conclusion, that the watch sometimes went wrcmg;, 
OF that it seldom went exaptly right. The pur* 
pose of the machinery, the design, and the de- 
signer, might be evident, and, in the case sup- 
posed, would be evident, in whatever way we 
accounted for the irregularity of the movement, 
or whether we could account for it or not. It ii 
not necessary that a machine be perfect, in order 
to show with what design it was made ; still less 
necessary, where the only question is, whether it 
were made with any design at all. 

III. Nor, thirdly, would it bring any uncer- 
tainty into the argimient, if there were a few parts 
pf the watch, concerning which we could not dis- 
cover, or had not yet discovered, in what manner 
they conduced to the general effect ; or even some 
parts, concerning which we could not ascertain 
whether they conduced to that effect in any man- 



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^(ATURAL THEOLOGYi 7 

ner wlu^tever. For, as to the first branch of the 
case, if by the loss, or disorder, or decay of the 
parts in question,, the movement of the watch were 
fijund in fact to be stopped, or disturbed, or re- 
tarded, no doubt would remain in our minds as to 
the utility or intention of these parts, although 
we should be unable to investigate the manner 
according to which, or the connexion by which^ 
the ultimate effect depended upon their action or 
assistance i ^nd the more complex is the machine, 
the more likely is this obscurity to arise. Then, 
as to the second thing supposed, namely, that 
there were parts which might be spared without 
prejudice to the movement of the watch, and that 
we had proved this by experiment, these super* 
fluous parte, even if we were completely assured 
that they were such, would not vacate the reai- 
s(ming which we had instituted concerning other 
parts. The indication of contrivance remained, 
with respect to them, nearly as it was before. > 
IV. Nor, fourthly, would any man in his senses 
think the existence of the watch, with its various 
machinery, accounted for, by being told that it 
was one out of possible combinations of material 
fonns ; that whatever he had found in the place 
where he found the watch,, must have contained 
some internal configuration or other ; and that 
this configuration might be the structure now ex- 



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8 NATURAL THEOLOGYr 

hibitcd^ viz., of the works of a watch, as well as a 
diflFcrent structure. 

V. Nor, fifthly, would it yield his inquiry more 
satisfaction, to be answered, that there existed in 
things a principle of order, which had disposed 
the parts of the watch into their present form and 
situation. He never knew a watch made by the 
principle of order ; nor can he even form to him- 
self an idea of what is meant by a principle of 
order, distinct from the intelligence of the watch- 
maker. 

VI. Sixthly, he would be surprised to hear that 
the mechanism of the watch was no proof of con- 
trivance, only a motive to induce the mind to 
think so : 

VII. And not less surprised to be informed, 
that the watch in his hand was nothing more than 
the result of the laws of metallic nature. It is a 
perversion of language to assign any law as the 
efficient, operative cause of anything. A law pre- 
supposes an agent ; for it is only the mode accord- 
ing to which an agent proceeds: it implies a 
power ; for it is the order according to which that 
power acts. Without this agent, without this 
power, which are both distinct from itself, the law 
does nothing, is nothing. The expression, " the 
law of metallic nature," may sound strange and 
harsh to a philosophic ear; but it seems quite as 



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NATURAL THEOLOGY. 9 

justifiable as some others which are more famiUar 
Id him, such as "the law of vegetable nature," 
''the law of animal nature," or, indeed, as "the 
law of nature" in general, when assigned as the 
cause of phenomena, in exclusion of agency and 
power, or when it is substituted into the place of 
these*. 

VIII. Neither, lastly, would our observer be 
driven out of his conclusion, or from his confidence 
in its truth, by being told that he knew nothing 
at all about the matter. He knows enough for 

* When philosophers and naturalists observe a certain 
succession in the phenomena of the universe, they con- 
sider the uniformity to exist through a law of nature. 
If they discover the order of events, or phenomena, they 
say they have discovered the law : for example, the law 
of afiinities, of gravitation, &c. It is a loose expression ; 
for to obey a law supposes an understanding and a will 
to comply. The phrase also implies that we know the 
nature of the governing power which is in operation, 
and in the present case both conditions are wanting. 

The "law" is the mode in which the power acts, 
and the term should infer, not only an acquiescence in 
the existence of the power, but of Him who has bestowed 
the power and enforced the law. 

The term " force " is generally used instead of power, 
when the intensities are measurable in their mechanical 
results. 

B 3 



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JO NATURAL THKQU>GT:. 

JbiB ftrgument: he Imows the utihty of the end; 
h^ kncfws the subserviency and adaptation of the 
jneans to the end. These pomts being known, 
.his i^orance of other points, his doubts concern^ 
ing other points, affect not the certainty of has 
reasoning. The consciousness of knowing little 
need not beget a distrust of that which he does 
know. 



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NATURAL T^SCXOGT; It 

CHAPTER II. 

STATE OF THE AR6«7BfENT €X>NTINUED. 

Suppose, in the next place, that the person who 
found the watdi should, ufter some time, discover 
that, in addition to all the properties whidi he 
had hitherto observed in it, it possessed the un* 
expected property of producing, in the course of 
its movement, another watch like itself (the thing 
is conceivable) ; that it contidned within it a me* 
cbanism, a system of parts, a mould, for instance, 
qr a complex adjustment of lathes, files, and other 
to<ds, evidently and separately csdculated for this 
purpose ; let us inquire what effect ought such a 
discovery to have upon his former conclusion. 

I. The first effect would be to increase his ad- 
miration of the contrivance, and his conviction of 
the consummate skill of the contriver. Whether 
be regarded the object of the contrivance, the dis- 
tinct apparatus, the intricate, yet in many parts 
intelligible mechanism by which it was carried on> 
he would perceive, in this new observation, nothing 
but an additional reason for doing what he had 
already done — for referring the construction of the 
watch to design, and to supreme art. If that con- 



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12 NATURAL TUBOLOOT. 

struction without this property, or which is the 
same thing, before this property had been no- 
ticed, proved intention and art to have been 
employed about it, still more strong would the 
proof appear, when he came to the knowledge of 
this further property, the crown and perfection of 
all the rest. 

II. He would reflect, that though the watdi be- 
fore him were, in some sense, the maker of the watch 
which was fabricated in the course of its move- 
ments, yet it was in a very different sense fix)m 
that in which a carpenter, for instance, is the 
maker of a chair — the author of its contrivance, 
the cause of the relation of its parts to their use. 
With respect to these, the first watch was no cause 
at all to the second ; in no such sense as this was 
it the author of the constitution and order, either 
of the parts which the new watch contained^ or of 
the parts by the aid and instrumentality of which 
it was produced. We might possibly say, but 
with great latitude of expression, that a stream of 
water ground corn ; but no latitude of expression 
would allow us to say, no stretch of conjecture 
could lead us to think, that the stream of water 
built the mill, though it were too ancient for us 
to know who the builder was. What the stream 
of water does in the affair is neither more nor less 
than this ; by the application of an unintelligent 



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KATURAL THEOLOGY. 13 

impulse to a mechanism previously arranged^ ar- 
ranged independently of it, and arranged by 
intelligence, an effect is produced, viz., the com is 
ground. But the effect results from the arrange- 
ment. The force of the stream cannot be said to 
be the cause or author of the effect, still less of 
the arrangement. Understanding and plan in the 
formation of the mill were not the less necessary 
for any share which the water has in grinding the 
com ; yet is this share the same as that which the 
watch would have contributed to the production 
of the new watch, upon the supposition assumed 
in the last section* Therefore, 

III. Though it be now no longer probable that 
the individual watch which our observer had found 
was made immediately by the hand of an artificer, 
yet doth not this alteration in anywise affect the 
inference, that an artificer had been originally 
employed and concerned in the production. The 
argument from design remains as it was. Marks 
of design and contrivance are no more accounted 
for now than they were, before. In the same 
thing, we may ask for the cause of different pro- 
perties. We may ask for the cause of the colour 
of a body, of its hardness, of its heat ; and these 
causes may be all different. We are now asking 
for the cause of that subserviency to a use, that 
relation to an end, which we have remarked in the 



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14 NATURAL THBOLOCnr; 

watdli before lis. Na answer is given to this 
question^ by telling ua that a preceding wat^ 
produced it. There cannot be design without a 
designer; contrivance, without a contriver; order, 
without choice; arrangement, without anything 
tapable of ajranging ; subserviency and relation 
^d a purpose, without that which could intend a 
purpose ; means suitable to an end, and executing 
their office in accomplishing that end, without the 
end ever having been contemplated, or the means 
accommodated to it. Arrangement, disposition 
bf parts, subserviency of means to an end, relation 
of instruments to a use, imply the presence of 
intelligence and mind. No one, therefore, can 
Irationally believe, that the insensible, inanimate 
watch, &om which the watch before vu& issued^ 
was the proper cause of the mechanism we so 
much admire in it; — could be truly said to have 
constructed the instrument, disposed its parts, 
assigned their office, determined their order, 
action, and mutual dependency, combined theix 
several motions into one result, and that also a 
result connected with the utilities of other beings. 
All these properties, therefore, are as much un- 
accounted for as they were b^bre. 

IV. Nor is anything gained by running the 
difficulty &xther back, L e., by suppo^g the watch 
before us to have been produced firom anotlie^ 



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J^ ATOItAL THEOIiOQr. 1 5 

3ratch> that £r6m a former> and so on indefinitdiy:: 
Oxa g^ing back evei: m> fax, brings us no neaxer 
io the least degree of statisfaetion upon the subject* 
Contrivance is still usaecounted £wr. We still want 
J* cpntriver. A designing mind is neither sup^ 
|died hy ^ais supposition^ nor dispensed with. If 
the difficulty were diminished the farther we went 
hmkjf by going back indefinitdy we might exhaust 
it. And this is the only case to which this sort 
of reasoning applies. Where there is a tendency, 
pv> as we increase the mimber of terms, a conti« 
jiual ap{»x>ach towards a limit, there, by supposing 
the number of terms to be what is caUed infinite^ 
we may conceive the limit to be attained; but 
wl^re there is no such t^jndency or approach, 
nothing is effected by lengthening the series* 
There is no difference as to the point in questicm 
(whatever there may be as to many points), be- 
tween one series and another; between a series 
which is finite, and a series which is infinite. A 
iehain> composed of an infinite number of links, 
can no mtore support itself than a chain composed 
of a finite number of links. And of this we are 
assured (though we never can have tried the ex- 
periment), because, by increasing the number of 
Unks, from ten for instance to a hundred, from a 
hundred to a thousand, &c., we make not the 
smallest approach, we observe not the smaller 



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16 KATURAL THEOLOGY. 

tendency, towards self-support. There is no dif- 
ference in this respect (yet there may be a great 
difference in several respects) between a chain of 
a greater or less length, between one chain and 
another/ between one that is finite and one that 
is infinite. This very much resembles the case 
before us. The machine which we are inspecting 
demonstrates, by its construction, contrivance and 
design. Contrivance must have had a contriver ; 
design, a designer ; whether the machine imme- 
diately proceeded from another machine or not. 
That circumstance alters not the case. That 
other machine may, in like manner, have pro- 
ceeded from a former macliine: nor does that 
alter the case ; the {jgntrivance must have had a 
contriver. That former one from one preceding 
it : no alteration still ; a contriver is still neces- 
sary. No tendency is perceived, no approach 
towards a diminution of this necessity. It is the 
same with any and every succession of these ma- 
chines ; a succession of ten, of a hundred, of a 
thousand; with one series, as with another; a 
series which is finite, as with a series which is 
infinite. In whatever other respects they may 
differ, in this they do not. In all, equally, con- 
trivance and design are unaccounted for. 

The question is not simply. How came the first 
watch into existence ? which question, it may be 



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NATURAL THEOLOGY. 17 

pretended, is done away by supposing the series 
of watches thus produced from one another to 
have been infinite, and consequently to have had 
no such, jftrst, for which it was necessary to provide 
a cause. This, perhaps, would have been nearly 
the state of the question, if nothing had been 
before us but an unorganised, unmechanised sub- 
stance, without mark or indication of contrivance. 
It might be difficult to show that such substance 
could not have existed from eternity, either in 
succession (if it were possible, which I think it is 
not, for unorganised bodies to spring from one 
another), or by individual perpetuity. But that 
is not the question now. To suppose it to be so, 
is to suppose that it made nqjjifference whether he 
had found a watch or a stone. As it is, the me- 
taphysics of that question have no place : for, in 
the watch which we are examining, are seen con- 
trivance, design ; an end, a purpose ; means for 
the end, adaptation to the purpose. And the 
question which irresistibly presses upon our 
thoughts, is. Whence this contrivance and de- 
sign ? The thing required is the intending mind, 
the adapted hand, the intelligence by which Ihat 
hand was directed. This question, this demand, 
is not shaken off, by increasing a number or suc- 
cession of substances, destitute of these proper- 
ties ; nor the more, by increasing that number to 



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18 JfkTlSBJLL THEOLOGY. 

mfinity. If it be said^ that> upon the suj^positioii 
of one watch being produced from another in the 
course of that other's movements^ and by means 
of the mechanism withm it, we have a cause for 
the watch in my hand, viz., the watch from which 
it proceeded, — I deny, that for the design, the 
•contrivance, the suitableness of means to an end, 
the adaptation of instruments to a use (all which 
we discover in the watch), we have any cause 
whatever. It is in vain, therefore, to assign a 
jseries of such causes, or to allege that a series 
may be carried back to infinity; for I do not 
jMlmit that we have yet any cause at all for the 
phenomena, still less any series of causes either 
jKnite or infinite. Here is contrivance, but no 
<^ntriver ; proofs of design, but no designer. 

V. Our observer would further also reflect, that 
the maker of the watch before him was, in truth 
and reality, the maker of every watch produced 
from it; there being no difference (except that 
the latter manifests a more exquisite skill) between 
the making of another watch with his own hands, 
by the mediation of files, lathes, chisels, &c., and 
the disposing, fixing, and inserting of these in- 
struments, or of others equivalent to them, in the 
body of the watch akeady made in such a manner, 
as to form a new watch in the course of the move- 
.ments which he had given to the old one. It is 



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. tiATUEAL THeOLO&Y> 19 

only working by. one set of tool$ instead of 
another. 

The conclu«ion which the first examinatiofi of 
the watch, of its works, construction, and move- 
inent, suggested^ was, that it must have had, tot 
the cause and author of that construction, an 
artificer who understood its mechanism and de- 
signed its use. This conclusion is invincible. A 
second examination presents us with a new dis- 
covery. The watch is found, in the course of its 
inoyement, to produce another watch, similar to 
itself; and not only so, but we perceive in it a 
system or organisation, separately calculated for 
that purpose. What effect would this discovery 
have, or. ought it to have, upon our former in- 
ference ? What, as hath already been said, but to 
increase, beyond measure, our admiration of the 
skill which had been employed in the formation 
of such a machine ? Or shall it, instead of this, 
all at once turn us round to an opposite conclu- 
sion, viz., that no art or skill whatever has been 
concerned in the business, although all other 
evidences of art and skill remain as they were, 
and this last and supreme piece of art be now 
added to the rest? Can this be maintained 
without absurdity ? Yet this is atheism.^ 

* We must leave this logical and satisfactory argument 



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20 KATURAL THEOLOGY. 

untouched* In this chapter our author is laying the 
foundation for a course of reasoning on the mechanism 
displayed in the animal body. The argument in favour 
of a creating and presiding Intelligence may be drawn 
from the study of the laws of physical agency : — such as 
the properties of heat, light, and sound ; of gravitation, 
and chemical combination ; the structure of the globe, 
the divisions of land and sea, the distribution of tempe- 
rature ; nay, the mind may rise to the contemplation of 
the sun and planets, their mutual dependence, and their 
revolutions ; but, as affording proofs obvious not only 
to cultivated reason but to plain sense, almost to ig- 
norance, there is nothing to be compared with that for 
which our author is preparing the reader in this chapter, 
the mechanism of the animal body, and the adaptations 
which affect the well-being of living creatures. 



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NATURAL THEOLOOT. 21 



CHAPTER III. 

APPLICATION OF THE ARGUMENT.' 

This is atheism : for every indication of contriv- 
ance, every manifestation of design, which existed 
in the watch, exists in the works of nature ; with 
the difference, on the side of nature, of being 
greater and more, and that in a degree which 
exceeds all computation. I mean that the con- 
trivances of nature surpass the contrivances of 
art, in the complexity, subtilty, and curiosity of 
the mechanism; and still more, if possible, do 
they go beyond them in number and variety ; yet, 
in a multitude of cases, are not less evidently 
mechanical, liot less evidently contrivances, not 
less evidently accommodated to their end, or 
suited to their oflBce, than are the most perfect 
productions of human ingenuity. 

• The arguments adduced in this chapter being drawn 
from the laws according to which light is refracted by 
the humours of the eye, the reader may be inclined to 
peruse the few observations on the elements of this part 
of physics in the Appendix, No. 16. 



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22 NXTORAL THEOLOGYr 




I know no better method of introducing so 
large a subject> than that of comparing a single 
thing with a single thing: an eye, for example, 
with a telescope. As far as the examination o£ 
the instrument goes, there is precisely the same 
proof that the eye was made for vision, as there is 
that the telescope was made for assisting it. They 
are made upon the same principles ; both being 
adjusted to the laws by which the transmission 
and refraction of rays of light are regulated. I 
speak not of the origin of the laws themselves ; 
but such laws being fixed, the construction in 
both cases is adapted to them. For instance; 
these laws require, in order to produce the same 
effect, that the rays of light, in passing from 
water into the eye, should be refracted by a more 
convex surface than when it passes out of air into' 
the eye. Accordingly we find that the eye of a 
fish, in that part of it called the crystalline lens, 
is much rounder than the eye of terrestrial 
animals, What plainer manifestation of design 
can there be than this differenee ? What could a 



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NATURAL theology; 63 

mathematical instrument maker have done more 
to show his knowledge of his principle, his appli- 
cation of that knowledge, his suiting of his means 
to his end ; I will not say to display the compass 
or excellence of his skill and art> for in these all 
comparison is indecorous, but to testify counsel^ 
choice, consideration, purpose ? ^ 

' The reader will find a comparison, more in detail, 
between the eye and optical instruments, in the Ap- 
pendix^ No. 17. 

In illustration of the instance adduced here, of the 
adaptation of the fish's eye to the medium in which it 
byes, we may observe that the powers in the human 
eye, for example, of drawing the pencil of rays to a 
fi>cu8, and producing an accurate image upon the ex- 
panded optic nerve (called the retina, from its net-work 
structure) in the bottom of the eye, depends princi- 
pally upon two circumstances, — ^the form of the cornea 
and the convexity of the lens. That the cornea may 
produce this effect, it is not only necessary that it should 
be convex, (as in the left-hand figure on page 22,) but 
that the rays should enter it from a rarer medium. As 
this cannot be effected in the water, the lens or crystal- 
line humour, which is much denser than water, is brought 
into operation. In the eye of an animal living in the 
atmosphere, the lens is removed backwards, and re- 
sembles the^ optician's double convex lens ; but in the 
fish it is a- sphere, and being brought in contact with the 



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24 NATURAL THEOLOGY. 

To some it may appear a difference sufficient 
to destroy all similitude between the eye and the 
telescope, that the one is a perceiving organ, the 
other an unperceiving instrument. The fact is 
that they are both instruments. And, as to the 
mechanism, at least as to mechanism being em^ 
ployed, and even asf to the kind of it, this circum- 
stance varies not the analogy at all. For observe 
what the constitution of the eye is. It is neces- 
sary, in order to produce distinct vision, that an 
image or picture of the object be formed at the 
bottom of the eye. Whence this necessity arises, 
or how the picture is connected with the sensa- 
tion, or contributes to it, it may be difficult, nay, 
we will confess, if you please, impossible for us to 

transparent cornea, it not only has the power to concen- 
trate the rays of light coming through the water, but 
by its altered position it increases greatly the sphere of 
vision* (See the right-hand figure, page 22.) To be 
critically correct, we may add that it is not exactly the 
cornea which is deficient in the fish, but the aqueous 
humour behind it. An aqueous fluid being thus both 
behind and before the cornea, and that membrane being 
in a very slight degree thicker in the centre than in the 
margin, this part of the organ which is so efficient in 
the atmosphere is rendered useless in water. A man 
diving, for example, sees imperfectly, being in some- 
thing worse than the condition of an old man who re- 
quires spectacles. 



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NATURAL THEOLOGY. 25 

search out. But the present question is not con- 
cerned in the inquiry. It may be true, that, in 
this, and in other instances, we trace mechanical 
contrivance a certain way; and that then we 
come to something which is not mechanical, or 
which is inscrutable. But this aflFects not the 
certainty' of our investigation, as far as we have 
gone. The difference between an animal and an 
automatic statue consists in this, — that, in the 
animal, we trace the mechanism to a certain point, 
and then we are stopped ; either the mechanism 
being too subtile for our discernment, or some- 
thing else beside the known laws of mechanism 
taking place ; whereas, in the automaton, for the 
comparatively few motions of which it is capable, 
we trace the mechanism throughout. But, up to 
the limit, the reasoning is as clear and certain in 
the one case as in the other. In the example 
before us, it is a matter of certainty, because it is 
a matter which experience and observation de- 
monstrate, that the formation of an image at the 
bottom of the eye is necessary to perfect vision. 
The image itself can be shown. Whatever affects 
the distinctness of the image, affects the distinct- 
ness of the vision. The formation then of such 
an image being necessary (no matter how) to the 
sense of sight, and to the exercise of that sense, 
the apparatus by which it is formed is constructed 



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26 NATURAL THEOLOGY. 

and put together, not only with infinitely more 
art, but upon the self-same principles of art, as in 
the telescope or the camera-obscura. The per* 
ception aridng from the image may be laid out of 
the question; for the production of the image, 
these are instruments of the same kind. The end 
is the same ; the means are the same. The pur^ 
pose in both k jJike ; the contrivance foi* accom- 
plishing that purpose is in both alike. The lenses 
of the telescopes, and the humours oi the eye, 
bear a complete resemblance to one another, in 
their figure, their position, and in their power 
over the rays of light, viz. in bringing each pencil 
to a point at the right distance from the lens ; 
namely, in the eye, at the exact place where the 
membrane is spread to receive it. How is it pos- 
sible, under circumstances ^f such close affinity> 
j«ad nider the operation of equal evidence, to 
exclude contrivance from the one; yet to acknow- 
ledge the proof of contrivance having been em- 
ployed, as the plainest and clearest of all propo- 
sitioiJSj in the other ? 

The resemblance between the two cases is stiir 
more accurate, and obtains in more points than 
we have yet represented, or than we are, on the^ 
first view of the subject, aware of In dioptric- 
telescopes there is an imperfection of this nature. 
Pencils of Ught in* passing through glass lenses^ 



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NATURAL THEOLOGY. 27- 

are separated into diflTerent colours, thereby ting- 
ing the object, especially the edges of it, as if it 
were viewed through a prism. To correct this 
inconvenience had been long a desideratum in 
the art. At last it came into the mind of a saga- 
cious optician, to inquire how this matter was 
managed in the eye : in which there was exactly 
the same difficulty to contend with as in the 
telescope. His observation taught him, that, 
in the eye, the evil was cured by combining 
lenses composed of diJBFerent substances, i. e. of 
substances which possessed different refracting 
powers. Our axtist borrowed thence his hint; 
and produced a correction of the defect by imitat- 
ing, in glasses made from different materials, the 
effects of the different humours through which 
the rays of light pifss before they reach the 
bottom of the eye. Could this be in tl|^ eye 
without purpose, which suggested to the optician 
the only effectual means of attaining that purpose® ? 

* This is an interesting part of the inquiry, ^hich 
will be found more fully explained in the Appendix. 

It is not, accurately speaking, " glasses of different 
refracting powers " which are required. Refraction is 
the new direction which the ray takes in passing from 
one transparent body into another of different density. 
Dispersion is the separation of the beam of light into 
differently coloured rays. A piece of glass may differ. 

e2- . 



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28 NATURAL THEOLOGY. 

But farther; there are other points, not so 
much perhaps of strict resemblance between the 
two, as of superiority of the eye over the tele- 
scope ; yet of a superiority which, being founded 
in the laws that regulate both, may fiimish topics 
of fair and just comparison. Two things were 
wanted to the eye, which were not wanted (at 
least in the same degree) to the telescope ; and 
these were the adaptation of the organ, first, to 
different degrees of light ; and secondly, to the 
vast diversity of distance at which objects are 
viewed by the naked eye, viz. from a few inches 
to as many miles. These difficulties present not 
themselves to the maker of the telescope. He 
wants all the light he can get; and he never 
directs his instrument to objects near at hand. 
In the eye, both these caseft were to be provided 
for ; ^yid for the purpose of providing for them, a 
subtile and appropriate mechanism is introduced. 

[The next figure represents a section of the anterior 
parti^he human eye:— A, A, the iris; B, the object, 
from which the rays strike off in all directions : a pencil 
of these enters at the pupil ; a portion is intercepted by 
the iris A, A. The pencil which enters the eye, passing 
through the lens, converges to form the image. But the 

from another in its power of refracting, and also in its 
property of dispersing. It is. by duly arranging these dif- 
ferent properties that the achromatic telescope is formed. 



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NATURAL THEOLOGY. 29 




A 

spaces C, C, are deprived of rays by the intervention of the 
iris A, A. Yet this in no measure affects the size of the 
image but only diminishes the intensity of its illumination. 
By the contraction of the iris, and consequent enlarge- 
ment of the pupil, a larger pencil of rays is admitted. 
It is remarkable that the image formed on the retina 
must always be inverted, and yet such is the power of 
habit and experience, derived from touching objects, 
that we see things as theyare in reality, and not as 
they are painted in our eyes — experience thus correcting 
the errors of sense. It js in the same way that we see 
single, though we have an image made in each eye. 
But if we change the ordinary position of our-^^e, the 
habit is broken, and we see double.] 

I. In order to exclude excess of light, when it 
is excessive, and to render objects visible^finder 
obscurer degrees of it, when no more can be had, 
the hole or aperture in the eye, through which 
the light enters, is so formed as to contract or 
dilate itself for the purpose of admitting a greater 
or less number of rays at the same time. The 
chamber of the eye is a camera-obscura, which, 
when the light is too smaU, can enlarge its open* 



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30 NATURAL THEOLOGY. 

ing ; when too strong, can again contract it; and 
that Tgdhout any other assistance than that of its 
own exquisite machinery. It is farther also, in 
the human subject, to be observed, that this hole 
in the eye, which we call the pupil, under all its 
different dimensions, retains its exact circular 
shape. This is a structure extremely artificial. 
Let an artist only try to execute the same; he 
will find that his threads and strings must be 
disposed with great consideration and contriv- 
ance, to make a circle which shall continually 
change its diameter yet preserve its form. This 
is done in the eye by an application of fibres, 
t. €, of strings similar, in their position and action, 
to what an artist would and must employ, if he 
had the same piece of workmanship to perform. 




[This figure represents the iris separated from the eye 
and laid out flat. We perceive the straight fibres pass- 
ing towards the inner margin, and the circular fibres 
running round the margin.] 



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NATURAL THEOLOOy. 31 

II. The second difficulty which has been stated 
was the suiting of the same organ to the^^ercep- 
tion of objects that lie near at hand^ within a few 
inches^ we will suppose, of the eye, and of olgects 
which are placed at a considerable distance firom 
it, that, for example, of as many furlongs (1 speak 
in both cases of the distance at which distinct 
vision can be exercised). Now this, according to 
the principles of optics, that is, according to the 
laws by which the transmission of light is regu- 
lated (and these laws are fixed), could not be 
done without the organ itself undergoing an alter- 
ation, and receiving an adjustment, that might 
correspond with the exigency of the case, that is 
to say, with the different inclination to one ano- 
ther under which the rays of light reached it. 
Bays issuing from points placed at a small dis- 
tance from the eye, and which consequently must 
enter the eye in a spreading or diverging order, 
cannot, by the same optical instrument in the 
same state, be brought to a point, i. e. be made to 
form an image, in the same place with rays pro- 
ceeding from objects situated at a much greater 
distance, and which rays arrive at the eye in direc- 
tions nearly (and physically speaking) parallel. 
It requires a rounder lens to do it. The point of 
concourse behind the lens must fall critically upon 
the retina, or the vision is confused; yet, other 



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32 NATURAL THEOLOGY. 

things remaining the same> this point, by the im- 
mutable properties of light, is carried farther back 
when tne rays proceed from a near object than 
when they are sent from one that is remote. 
A person who was using an optical instrument 
would manage this matter by changing, as the 
occasion required, his lens or his telescope, or by 
adjusting the distance of his glasses with his hand 
or his screw : but how is this to be managed in 
the eye ? What the alteration was, or in what 
part of the eye it took place, or by what means it 
was effected (for if the known laws which govern 
the refraction of light be maintained, some altera- 
tion in the state of the organ there must be), had 
long formed a subject of inquiry and conjecture. 
The change, though sufficient for the purpose, is 
so minute as to elude ordinary observation. Some 
very late discoveries, deduced from a laborious and 
most accurate inspection of the structure and ope- 
ration of the organ, seem at length to have ascer- 
tained the mechanical alteration which the parts 
of the eye undergo. It is found, that by the 
action of certain muscles, called the straight mus- 
cles, and which action is the most advantageous 
that could be imagined for the purpose, it is found 
I say, that whenever the eye is directed to a near 
object, three changes are produced in it at the 
same time, all severally contributing to the adjust- 



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NATURAL THEOLOGY* iJ3 

ment required^ The cornea, or outermost coal of 
the eye, is rendered more round and pronjinent ; 
the crystalline lens underneath is pushed forward ; 
and the axis of vision^^ as the depth of the eye is 
called^ is elongated. These changes in the eye 
vary its power over the rays of light in such a 
manner and degree as to produce exactly the 
effect which is wanted, viz. the formation of an 
image upon the retinuy whether the rays come to 
the eye in a state of divergency, which is the case 
when the object is near to the eye, or come paral- 
lel to one another, which is the case when the 
object is placed at a distance. Can anything be 
more decisive of contrivance than this is ? The 
most secret laws of optics must have been known 
to the author of a structure endowed with such a 
capacity of change. It is as though an optician, 
when he had a nearer object to view, should rec- 
tify his instrument by putting in another glass, at 
the same time drawing out also his tube to a dif- 
ferent length*. 

• This is a subject over which there is still great ob- 
scurity, and on which adverse experiments and opinions 
are recorded. However difficult it may be to account 
for the mode of adjustment, yet the property is not de- 
nied, and therefore the argument in the text rcmwns, 

c3 



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34 NATURAL THEOLOGY. 

Observe a new-born child first lifting up its eye* 
Uds. What does the opening of the curtain dis* « 
cover ? The anterior part of two pellucid globes^ 
which^ when they come to be e^camined, are found 

That there is something in the sensibility of the nerve, 
and in the power of attention, there seems no doubt. 
Birds of prey, it has been noticed, possess a power of 
vision of which we can hardly form a conception. 
Where it is the object to snare the falcon, a pigeon is 
tied, in an exposed situation, with a cord so attached that 
a person concealed can flutter the bird, or make it extend 
its wings ; and although no bird of prey be visible in 
the whde sky, presently the hawk will be seen descend- 
ing to pounce upon the pigeon. The endowment of the 
bird's eye must be different from ours, else the bird of 
prey could not see the most minute object when hover- 
ing at a great height ; nor, in sweeping down upon his 
quarry, could he strike it with precision. Nothing of the 
n^Rure of mere mechanical provision can accomit for the 
possession of this superior power. One instance of the 
power of adjustment which the eye has under the influ- 
ence of the will, seems to be this. Let a person who 
cannot read distinctly, or at aU, without spectacles, at 
a given distance, look at a word through a very small 
aperture, and he will see what he before could not with- 
out spectacles. This can hardly be explained by the 
removal of the lateral hght, or by inflexicm. 



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NATURAL THEOLOGY. 35 

to be constructed upon strict optical principles ; 
* the self-same principles upon which we ourselves 
cionstruct optical instruments. We find them 
perfect for the purpose of forming an image by- 
refraction; composed of parts executing different 
offices: one part having fulfilled its office upon 
the pencil of Hght, delivering it over to the action 
of another part ; that to a third, and so onward : 
the progressive action depending for its success 
upon the nicest and minutest adjustment of the 
parts concerned : yet these parts so in fact ad- 
justed as to produce, not by a simple action or 
effect, but by a combination of actions and effects, 
the result which is, ultimately wanted. And for- 
asmuch as this organ would have to operate under 
different circumstances, with strong degrees of 
light and with weak degrees, upon near objects 
and upon remote ones, and these differences de- 
manded, according to the laws by which the trans- 
mission of light is regulated, a corresponding 
diversity of structure, — that the aperture, for ex- 
ample, through which the light passes should be 
larger or less — the lenses rounder or flatter — or 
that their distance from the tablet upon which the 
picture is delineated should be shortened or 
lengthened — this, I say, being the case and the 
difficulty to which the eye was to be adapted, we 
find its several parts capable of being occasionally 



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36 NATURAL THEOLOGY. 

changed^ and a most artificial apparatus provided 
to produce that change. This is far beyond the 
common regulator of a watch, which requires the 
touch of a foreign hand to set it ; but it is not alto- 
gether unlike Harrison's contrivance for making a 
watch regulate itself, by inserting within it a ma- 
chinery which, by the artful use of the different ex- 
pansion of metals, preserves the equability of the 
motion under aU the various temperatures of heat 
and cold in which the instrument may happen to 
be placed. The ingenuity of this last contrivance 
has been justly praised. Shall, therefore, a struc- 
ture which differs from it chiefly by surpassing it, 
be accoimted no contrivance at all ? or, if it be a 
contrivance, that it is without a contriver ? 

But this, though much, is not the whole : by 
different species of animals the faculty we are de- 
scribing is possessed in degrees suited to the dif- 
ferent range of vision which their mode of life 
and of procuring their food requires. Birds, for 
instance, in general, procure their food by means 
of their beak ; and, the distance between the eye 
and the point of the beak being small, it becomes 
necessary that they should have the power of 
seeing very near objects distinctly. On the other 
hand, from being often elevated much above the 
ground, living in the air, and moving through it 
with great velocity, they requke for their safety. 



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NATURAL THEOLOGY^ 37 

as well as for assisting them in descrying their 
prey, a power of seeing at a great distance; 9, 
power of which, in birds of rapine, surprising ex- 
amples are given. The fact accordingly is, that 
two peculiarities are found in the eyes of birds, 
both tending to facilitate the change upon which 
the adjustment of the eye to diflFerent distances 
depends. The one is a bony, yet, in most species^, 
a flexible rim or hoop, surrounding the broadest 
part of the eye, which, confining the action of the 
muscles to that part, increases the effect of their 
lateral pressure upon the orb, by which pressure 
its axis is elongated for the purpose of looking at 
very near objects. The other is an additional 
muscle, called the marsupium, to draw, on occa- 
sion, the crystalline lens back, and to fit the same 
eye for the viewing of very distant objects. By 
these means, the eyes of birds can pass from one 
extreme to another of their scale of adjustment, 
with more ease and readiness than the eyes of 
other animals. 

The eyes of fishes also, compared with those of 
"ferrestrial animals, exhibit certain distinctions of 
structure, adapted to their state and .element. 
We have already observed upon the figure of the 
crystalline compensating by its roundness the 
density of the medium through which their light 
passes. To which we have to add, that the eyes 



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38 NATURAL THEOLOGY. 

offish^ in their natural and indolent state^ appear * 
to be adjusted to near objects, in this respect dif- 
fering from the human eye, as well as those of 
quadrupeds and birds. The ordinary shape of 
the fish's eye being in a much higher degree con- 
vex than that of land animals, a corresponding 
difference attends its muscular conformation, viz., 
that it is throughout calculated for flattening the 
eye. 

The iris also in the eyes of fish does not admit 
of contraction. This is a great difference, of which 
the probable reason is, that the diminished light 
in water is never too strong for the retina. 




In the eel, which has to worlc'^it's head through 
sand and gravel, the roughest and harshest sub- 
stances, there is placed before the eye, iStid at 
some distance from it, a transparent, homy, con- 
vex case or covering, which, without obstructing 
the sight, defends the organ. To such an animal 
could anjrthing be more wanted or more useful ? 

Thus, in comparing the eyes of different kinds 
of animals, we see in their resemblances and dis- 



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NATURAL THEOLOGY. 39 

tinciions one general plan laid down^ and that 
plan varied with the varying exigencies to which 
it is to be applied^**. 

^' In viewing the structure of the eye as adjusted to 
the condition of fishes, we may remark the peculiar 
thickness of the sclerotic coat in the whale. Although 
he breathes the atmosphere, and lies out on the surface 
of the water ; to escape his enemies he will plunge some 
hundred fathoms deep. The pressure therefore must he 
very great upon his surface, and on the surface of the eye. 
If a cork be knocked into the mouth of a bottle, so that 
it resists all further pressure that we can make upon it, 
and if this bottle be carried, by being attached to the 
sounding-lead, to a great depth m the sea, the pressure 
of the water will force in the cork, and fill the bottle ; 
for the cork is pressed with a force equal to the weight 
of the column of water above it, of which it is the base. 
It is pressed in all directions equally, so that a common- 
sized cork is reduced to the size of that of a phial bottle. 

" A creature Uving at the depth of 100 feet would 
sustain a pressure, including that of the atmosphere, of 
about 60 pounds on the square inch ; while one at 4000 
feet, a depth by no means considerable, would be ex- 
posed to a pressure of about 1830 pounds upon the 
square inch." — De La Beche, Theor, GeoL p. 243. 

We can therefore comprehend how it shall happen, 
that on the foundering of a ship at sea, though its tim- 
bers part, not a spar floats to the surface ; everything is 
swallowed up ; for, if the hull has sunk to a great depth. 



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40 NATURAL THEOLOGY, 

There is one property, however, common, I be^ 
lieve, to all eyes, at least to all which have been 
examined*, namely, that the optic nerve enters 

all that is porous is penetrated with water, or compressed, 
and consequently remains where it sunk. So it hap- 
pened, and the fact goes directly to our purpose, that 
when, by the entangling of the line of the harpoon, the 
boat was carried down with the whale, and, being reco- 
vered, it required two boats to keep it at the surface.-^ 
Scoresby, 

We may easily conceive, therefore, the pressure which 
the eye of the whale sustains when it dives, and why it is 
formed with the provisions which we are about to describe. 
When we make a section of the whole eye, cutting 
through the cornea, the sclerotic coat, which is dense eq 
tanned leather, increases in thickness towards the back 
part^ and is full five times the thickness behind, that it 
is at the anterior part. The anterior part of the eye 
sustains the pressure from without, and requires no addi- 
tional support; but were the back part to yield, the 
globe would be then distended in that direction, and the 
whole interior of the eye consequently suffer derange- 
ment. We perceive, therefore, the necessity of the coats 
being thus so remarkably strengthened behind. The 
natural enemies of the whale are the sword-fish and the 
shark ; and it is stated with some show of reason, that 
this huge creature, being without means of defence of 

* The eye of the seal or sea-calf, I understand, is an exception. 
Mem. Acad. Paris, 1710, p. 123.— Pa/<ry, 



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NATURAL THEOLOGT. 41 

the bottom of the eye, not in the centre or middle^ 
but a little on one side : not in the point where 
the axis of the eye meets the retina, but between 
that point and the nose. The difference which 
this makes is, that no part of an object is unper- 
ceived by both eyes at the same time. 

In considering vision as achieved by the means 
of an image formed at the bottom of the eye, we 
c^n never reflect without wonder upon the small* 
ness yet correctness of the picture, the subtilty of 
the touch, the fineness of the lines. A landscape of 
five or six square leagues is brought into a space 
of half an inch diameter; yet the multitude of 
objects which it contains arfe all preserved, are 
all discriminated in their magnitudes, positions, 
figures, colours. The prospect firom Hampstead- 
hill is compressed into the compass of a sixpence, 
yet circumstantially represented. A stage-coach, 
travelling at an ordinary speed for half an hour, 
passes, in the eye, only over one-twelfth of an inch, 
yet is this change of place in the image distinctly 
perceived throughout its whole progress ; for it is 

any kind, carries his enemies that have fixed upon hira 
to a depth of water, and consequently to a pressure, 
which subdues them, as their bodies are not con8titute4 
for such depths. It is under this instinct, that when the 
whale receives the harpoon, he dives to the bottom. 



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42 NATURAL THEOLOGY. 

only by means of that perception that the motion 
of the coach itself is made sensible to the eye. If 
anything can abate our admiration of the small- 
ness of the visual tablet compared with the extent 
of vision, it is a reflection which the view of nature 
leads us every hour to make, viz., that, in the 
hands of the Creator, great and little are nothing. 
Sturmius held, that the examination of the eye 
was a cure for atheism. Besides that conformity 
to optical principles which its internal consti- 
tution displays, and which alone amounts to a 
manifestation of intelligence having been exerted 
in the structure; besides this, which forms, no 
doubt, the leading character of the organ, there 
is to be seen, in everything belonging to it and 
about it, an extraordinary degree of care, an 
anxiety for its preservation, due, if we may so 
speak, to its value and its tenderness. It is 
lodged in a strong, deep, Tbony socket, composed 
by the junction of seven different bones*, hol- 
lowed out at their edges. In some few species, 
as that of the coatimondif, the orbit is not bony 
throughout; but whenever this is the case, the 
upper, which is the deficient part, is supplied by 
a cartilaginous ligament; a substitution which 
shows the same care. Within this socket it is 
embedded in fat, of all animal substances the best 

• Heister, sect. 89. f Mem. R. Ac. Paris, p. 117.— Pa/<ry. 



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NATURAL THEOLOGY. 43 

lulapted both to its repose and motion. It is 
sheltered by the eyebrows — an arch of hair, which, 
like a thatched penthouse, prevents the sweat 
«md moisture of the forehead from running down 
into it. 

But it is still better protected by its lid. Of 
the superficial parts of the animal frame, I know 
none which, in its office and structure, is more 
diserving of attention than the eyelid. It defends 
the eye ; it wipes it ; it closes it in sleep. Are 
there, in any work of art whatever, purposes more 
evident than those which this organ frilfils ? or an 
apparatus for executing those purposes more in- 
telligible, more appropriate, or more mechanical ? 
If it be overlooked by the observer of nature, it 
can only be because it is obvious and familiar. 
This is a tendency to be guarded against. We 
pass by the plainest instances, whilst we are ex* 
ploring those which are rare and curious; by 
which conduct of the understanding, we some- 
limes neglect the strongest observations, being 
taken up with others which, though more recon- 
dite and scientific, are, as solid arguments, entitled 
to much less consideration. 

In order to keep the eye moist and clean (which 
qualities are necessary to its brightness and its 
use), a wash is constantly supplied by a secre- 
tion for the purpose ; and the superfluous brine is 



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44 NATURAL THEOLOGY. 

conveyed to the nose through a perforation in the 
bone as large as a goose-quill. When once the 
fluid has entered the nose^ it spreads itself upon 
the inside of the nostril, and is evaporated by the 
current of warm air which, in the course of respi- 
ration, is continually passing over it. Can any 
pipe or outlet, for carrying off the waste liquor 
from a dye-house or a distillery, be more mecha- 
nical than this is ? It is easily perceived that tbe 
eye must want moisture : but could the want of 
the eye generate the gland which produces the 
tear, or bore the hole by which it is discharged— 
a hole through a bone ? 

It is observable that this provision is not found 
in fish — the element in which they live supplying 
a constant lotion to the eye". 

It were, however, injustice to dismiss the eye as 

a piece of mechanism, without noticing that most 

♦ 

" We have entered into a much fuller explanation of 
the apparatus for the preservation of the eye, in the Ap- 
pendix, there being a great deal that is curious in it 
hitherto unnoticed. It will be there found that, although 
the eye of the fish has no eyelid, yet it has the rapid 
motion of the eye-ball, which, under water, must serve 
to free it from any impurity. Some curious instances are, 
at the same time, afforded, of a still more artificial mode, 
in the lobster and crab, of removing whatever obstructs 
the sight. 



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NATURAL THEOLOGY. 45' 

exquisite of all contrivances, the nictitating mem-' 
brane, which is found in the eyes of birds, and of 
many quadrupeds. Its use is to sweep the eye, 
which it does in an instant ; to spread over it the 
lachrymal hiunour ; to defend it also from sudden 
injuries; yet not totally, when drawn upon the 
pupil, to shut out the light. The commodious- 
ness with which it lies folded up in the upper 
cqpier of the eye, ready for use and action, and 
the quickness with which it executes its purpose, 
are properties known and obvious to every ob- 
server; but what is equally admirable, though 
not quite so obvious, is the combination of two 
kinds of substance, muscular and elastic, and of 
two different kinds of action, by which the motion 
of this membrane is performed. It is not, as iy 
ordinary cases, by the action of two antagonist 
muscles, one pulling forward, and the other back- 
ward, that a reciprocal change is effected ; but it 
is thus: the membrane itself is an elastic sub- 
stance, capable of being drawn out by force like 
a piece of elastic gum, and by its own elasticity 
returning, when the force is removed, to its former 
position. Such being its nature, in order to fit it 
up for its office, it is connected by a tendon or 
thread with a muscle in the back part of the eye : 
this tendon or thread, though strong, is so fine as 
not to obstruct the sight, even when it passes 



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46 NATURAL THEOLOGY. 

across it ; and the muscle itself, being placed in 
the back part of the eye, derives from its situation 
the advantage, not only of being secure, but of 
being out of the way ; which it would hardly have 
been in any position that could be assigned to it 
in the anterior part of the orb, where its function 
lies. When the muscle behind the eye contracts, 
the membrane, by means of the communicating 
thread, is instantly drawn over the fore-part of it. 
When the muscular contraction (which is a posi- 
tive and, most probably, a voluntary effort) ceases 
to be exerted, the elasticity alone of the membrane 
brings it back again to its position*. Does not 
this, if anything can do it, bespeak an artist, mas- 
ter of his work, acquainted with his materials? 
" Of a thousand other things," say the French 
Academicians, "we perceive not the comJivance, 
because we understand them only by their effects, 
of which we know not the causes : but we here 
treat of a machine, all the parts whereof are 
visible, and which need only be looked upon to 
discover the reasons of its motion and actionf ." 

In the configuration of the muscle which, though 
placed behind the eye, draws the nictitating mem- 

♦ Phil. Trans. 1796. 

t Memoirs for a Natural History of Animals, by the Royal 
Academy of Sciences at Paris, done into English by order of the 
Royal Society, 1701, p. 249.— PoAfy 



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NATURAL THEOLOGY. 47 

brane over the eye, there is, what the authors just 
now quoted deservedly call a marvellous mechan- 
ism. I suppose this structure to be found in 
other animals; but, in the memoirs from which 
this account is taken, it is anatomically demon- 
strated only in ihe cassowary. The muscle is 
passed through a loop formed by another muscle ; 
and is there inflected as if it were round a pulley. 
This is a peculiarity, and observe the advantage 
of it. A single muscle with a straight tendon, 
which is the common muscular form, would have 
been sufficient, if it had had power to draw far 
enough. But the contraction necessary to draw 
the membrane over the whole eye, required a 
longer muscle than could lie straight at the bottom 
of the eye. Therefore, in order to have a greater 
length ifl^a less compass, the cord of the main 
muscle makes an anglfe. This so far answers the 
end; but, still farther, it makes an angle, not 
round a fixed pivot, but round a loop formed by 
another muscle, which second muscle, whenever it 
contracts, of course twitches the first muscle at 
the point of inflection, and thereby assists the 
action designed by both^'. 

" There is one effect, however, of this apparal^us, 
which our author has omitted to notice — that is, the 
rapidity of motion in the membra/na nictitan&y produced 



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48 NATURAL THEOLOGY. 

One question may possibly have dwelt in the 
reader's mind during the perusal of these ob- 
servations, namely. Why should not the Deity 
have given to the animal the faculty of vision at 
once? Why this circuitous perception; the mi- 
nistry of so many means ; an element provided 
for the purpose; reflected from opaque sub- 
stances, refracted through transparent ones ; and 
both according to precise laws ; then, a complex 
organ, an intricate and artificial apparatus, in 
order, by the operation of this element, and in 

by the oblique direction and junction of the tendons of 
these muscles. This will be illustrated hereafter. 

The membrana nictitans is peculiar to birds : the 
term is not applicable to the corresponding fc-ucture in 
quadrupeds, the object being there obtained by a very 
different - mechanism. The Juiw is a thin cartilage, 
which, lying between the eye-ball and the inner part of 
the orbit, flies rapidly out, and sweeps the surface of the 
eye in a manner much more perfect than can be per- 
formed by the outer eyelids. Every one who has ridden 
a horse in a dusty road, must have been struck with the 
superior provision in the horse's eye : he never sufiers 
from the dust, because, this cartilage, being bedewed by 
the secretion of a pecuhar gland, not tears, but a matter 
more glutinous, sweeps across the eye, and collects and 
removes every particle of dust. 



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NATURAL THEOLOGY. 49 

conformity with the restrictions of these laws, to 
produce an image upon a membrane communi- 
cating with the brain ? Wherefore all this ? Why 
make the difficulty in order to surmount it ? If 
to perceive objects by some other mode than that 
of touch, or objects which lay out of the reach of 
that sense, were the thing proposed, could not a 
simple volition of the Creator have communicated 
the capacity ? Why resort to contrivance, where 
power is omnipotent? Contrivance, by its very 
definition and nature, is the refiige of imperfec- 
tion. To have recourse to expedients implies 
difficulty, impediment, restraint, defect of power. 
This question belongs to the other senses, as well 
as to sight; to the general functions of animal 
life, as nutrition, secretion, respiration ; to the 
feconomy of vegetables ; and indeed to s^most all 
the operations of nature. The question, there- 
fore, is of very wide extent ; and amongst, other 
answers which may be given to it, besides reasons 
of which probably we are ignorant, one answer is 
this : It is only by the display of contrivance that 
the existence, the agency, the wisdom of the 
Deity, could be testified to his rational creatures. 
This is the scale by which we ascend to all the 
knowledge of our Creator which we possess, so 
far as it depends upon the phenomena, or the 
works of nature. Take away this, and you take 

D 



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50 NATURAL THEOLOGY. 

away from us every subject of observation, and 
ground of reasoning ; I mean, as our rational 
faculties are formed at present. Whatever is 
done, God could have done without the interven- 
tion of instruments or means ; but it is in the 
construction of instruments, in the choice and 
adaptation of means, that a creative intelligence 
is seen. It is this which constitutes the order 
and beauty of the universe. God, therefore, has 
been pleased to prescribe limits to his own power, 
and to work his ends within those limits." The 
general laws of matter have perhaps prescribed the 
nature of these limits ; its inertia, its reaction ; the 
laws which govern the communication of motion, 
the refraction and reflection of light, the constitu- 
tion of fluids non-elastic and elastic, the transmis- 
sion of sound through the latter; the laws of 
magnetism, of electricity; and probably others, 
yet undiscovered. These are general laws ; and 
when a particular purpose is to be efiected, it is 
not by making a new law, nor by the suspension of 
the old ones, nor by making them wind, and bend, 
and yield to the occasion (for nature with great 
steadiness adheres to and supports them) ; but it 
is, as we have seen in the eye, by the interposition 

" This subject is touched upon in the introductory 
observations to the Appendix, 



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NATURAL THEOLOGY. 51 

of an apparatus, corresponding with these laws, 
and suited to the exigency which results from 
them, that the purpose is at length attained. As 
we have said, therefore, God prescribes limits to 
his power, that he may let in the exercise and 
thereby exhibit demonstrations of his wisdom. 
For then, L e,, such laws and limitations being 
laid down, it is as though one Being should have 
fixed certain rules, and, if we may so speak, 
provided certain materials, and afterwards have 
committed to another Being, out of these mate- 
rials, and in subordination to these rules, the 
task of drawing forth a creation : a supposition 
which evidently leaves room, and induces indeed 
a necessity for contrivance. Nay, there may be 
many such agents, and many ranks of these. We 
do not advance this as a doctrine either of philo- 
sophy or of religion ; but we say that the subject 
may safely be represented under this view ; be- 
cause the Deity, acting himself by general laws, 
will have the same consequences upon our reason- 
ing, as if he had prescribed these laws to another. 
It has been said, that the problem of creation 
was, *' attraction and matter being given, to make 
a world out of them;" and, as above explained, 
this statement perhaps does not convey a false 
idea. 



d2 



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52 NATURAL THEOLOGY. 

We have made choice of the eye as an instance 
upon which to rest the argument of this chapter. 
Some single example was to be proposed; and 
the eye oflfered itself under the advantage of ad- 
mitting of a strict comparison with optical instru- 
ments. The ear, it is probable, is no less artifi- 
cially and mechanically adapted to its office than 
the eye. But we know less about it : we do not 
so well understand the action, the use, or the 
mutual dependency of its internal parts.'* Its 

" The reader will find a dissertation on the ear in the 
Appendix. Other authors, as well as Dr. Paley, have 
said that we do not imderstand the uses or mutual 
dependency of the internal parts of the ear: an ob- 
servation either not very intelligible, or which shows 
them to have studied it superficially. 




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NATURAL THEOLOGY. 53 

general form, however^ both external and inter- 
nal, is sufficient to show that it is an instrument 

Explanation of the Plan of the Ear. — ^A, the tube of 
the ear, having little glands to secrete the wax, and hairs 
standing across it to exclude insects, without impeding 
the vibrations of the atmosphere ; B, the membrane of 
the tympanum drawn into the form of a funnel by the 
attachment of the malleiLS ; C, the chain of four bones 
lying in the irregular cavity of the tympanum^ and com- 
municating the vibrations of the membrane B to the 
fluid in the labyrinth; D, Eustachian tube, which 
forms a communication between the throat and the 
iympanumy so as to preserve an equilibrium of the air 
in the cavity of the tympanum and the atmosphere; 
E, F, the labyrinth, consisting of a central cavity, the 
vestibule; the three semicircular canals, E, and the 
cochleay F. 

Beginning from the left hand we have the malleus^ 
or hammer, the first of the chain of bones ; we see the 
long handle or process which is attached to the mem- 
brane of the tympanum^ and which moves with the 
vibrations of that membrane ; the other end is enlarged, 
and has a groove upon it which is articulated with the 
next bone. The second bone is the incusy or anvil, to 
the grooved surface of which the malleus is attached. 
A long process extends from this bone, which has upon 
it the OS orbicular e; and to this third bone there is 
attached a fourth, the stapes, which is in shape like a 
stirrup iron. The base of this bone is of an oval shape, 



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54 NATURAL THEOLOGY. 

adaplied to the reception of sound; that is to say> 
ah*eady knowing that sound consists in pulses of 
the air, we perceive, in the structure of the ear, a 
suitableness to receive impressions from this spe- 
cies of action, and to propagate these impressions 
to the brain. For of what does this structure 
consist? An external ear (the concha), calcu- 
lated, like an ear trumpet, to catch and collect 
the pulses of which we have spoken; in large 
quadrupeds, turning to the sound, and possessing 
a configuration, as well as motion, evidently fitted 
for the oflSce : of a tube which leads into the 
head, lying at the root of this outward ear, the 
folds and sinuses thereof tending and conducting 
the air towards it : of a thin membrane, like the 
pelt of a drum, stretched across this passage 
upon a bony rim : of a chain of movable and in- 
finitely curious bones, forming a communication, 
and the only communication that can be obser\^ed, 
between the membrane last mentioned and the 

and rests upon a membrane which closes the hole leading 
into the labyrinth. This hole is called foramen ovale. 
The plan of the cochlea shows that one of its spiral 
passages, beginning in the vestibule, winds round the 
pillar till it meets in a point with another tube. If the 
eye follow this second spiral tube, it will be found to 
lead, not into the vestibule, but into the irregular cavity 
of the tympanum. 



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NATURAL THEOLOGY. 55 

interior channels and recesses of the skull : of 
cavities, similar in shape and form to wind instru- 
ments of music, being spiral or portions of circles : 
of the eustachian tube, like the hole in a drum, to 
let the air pass freely into and out of the barrel 
of the ear, as the covering membrane vibrates, or 
as the temperature may be altered: the whole 
labyrinth hewn out of a rock ; that is, wrought 
into the substance of the hardest bone of the 
body. This assemblage of connected parts con- 
stitutes together an apparatus plainly enough 
relative to the transmission of sound, or of the 
impulses received from sound, and only to be la- 
mented in not being better understood. 




The communication within, formed by the small 
bones of the ear, is, to look upon, more like what 
we are accustomed to call machinery, than any 
thing I am acquainted with in animal bodies. It 
seems evidently designed to continue towards the 
sensorium the tremulous motions which are ex- 
cited in the membrane of the tympanum, or what 
is better known by the name of the " drum of the 



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56 NATURAL THEOLOGY. 

ear.'* The compages of bones consists of four. 




[ This figure represents the bones which form 
the chain.] 

which are so disposed, and so hinge upon one 
another, as that if the membrane, the drum of the 
ear, vibrate, all the four are put in motion toge- 
ther ; and, by the result of their action, work the 
base of that which is the last in the series, upon 
an aperture which it closes, and upon which it 
plays, and which aperture opens into the tortuous 
canals that lead to the brain. This last bone of 
the four is called the stapes. The office of the 
drum of the ear is to spread out an extended 
surface, capable of receiving the impressions of 
sound, and of being put by them into a state of 
vibration. The office of the stapes is to repeat 
these vibrations. It is a repeating frigate, sta- 
tioned more within the line. From which account 
of its action may be understood how the sensa- 
tion of sound will be excited by any thing which 
communicates a vibratory motion to the stapes, 
though not, as in all ordinary cases, through the 
intervention of the membrana tympani. This is 



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NATURAL THEOLOGY. 57 

done by solid bodies applied to the bones of the 
skuU^ as by a metal bar holden at one end between 
the teeth, and touching at the other end a tremu- 
lous body. It likewise appears to be done, in a 
considerable degree, by the air itself, even when 
this membrane, the drum of the ear, is greatly 
damaged. Either in the natural or preternatural 
state of the organ, the use of the chain of bones 
is to propagate the impulse in a direction towards 
the brain, and to propagate it with the advantage 
of a lever ; which advantage consists in increasing 
the force and strength of the vibration, and at 
the same time diminishing the space through 
which it oscillates; both of which changes may 
augment or facilitate the still deeper action of the 
auditory nerves." 

The benefit of the eustachian tube to the or- 
gan may be made out upon pneumatic principles. 

" It will be shown in the Appendix, that the fine 
apparatus consisting of these bones, with their four 
minute muscles attached to them, is not necessary to 
the sensation coming through the bones of the head, as 
here described by our author: it is provided for the 
more delicate vibrations of the elastic atmosphere, and 
is not found except in animals that breathe the air. It 
will be also found, that whilst these bones move with 
the slightest impulse of sound, they regulate the impres- 
sion, and protect the nerve. 

d3 



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58 NATURAL THEOLOGY. 

Behind the drum of the ear is a second cavity, 
or barrel, called the tympanum. The eustadiian 
tube is a slender pipe, but sufficient for the 
passage of air, leading from this cavity into the 
back part of the mouth. Now, it would not have 
done to have had a vacuum in this cavity ; for, in 
that case, the pressure of the atmosphere from 
without would have burst the membrane which 
covered it Nor would it have done to have filled 
the cavity with lymph, or any other secretion ; 
which would necessarily have obstructed, both the 
vibration of the membrane, and the play of the 
small bones. Nor, lastly, would it have done to 
have occupied the space with confined air, because 
the expansion of that air by heat, or its contrac- 
tion by cold, would have distended or relaxed the 
covering membrane, in a degree inconsistent with 
the purpose which it was assigned to execute. 
The only remaining expedient, and that for which 
the eustachian tube serves, is to open to this 
ca\ity a communication with the external air. In 
one word, it exactly answers the purpose of the 
hole in a drum. 

The membrana tympani itself, likewise, de- 
serves all the examination which can be made of 
it. It is not found in the ears offish ; which fiir- 
nishes an additional proof of what indeed is indi- 
cated by every thing about it, that it is appro- 



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NATURAL THEOLOGY. 59 

priaied to the action of air^ or of an elastic 
medium. It bears an obvious resemblance to the 
pelt or head of a drum^ from which it takes its 
name. It resembles also a drum-head in this 




[This figure represents the membrane of the tym- 
panum of a larger size than natural. It is represented 
as tucked in by the handle of the malleus. The de- 
scription of Sir Everard Home, referred to in the text, 
is altogether fanciful. There is no proof that these fibres 
are muscular : they are drawn tight by the small muscle 
attached to the malleus called tensor tympani ; and it 
would appear that these cords are necessary to produce 
that variety of motion in the membrane suited to all the 
variety of sounds which are conveyed through it to 
the seat of the sense. Sir Everard played to the ele- 
phant on the piano-forte. That the animal took some 
notice of the extraordinary sound cannot surprise us; 
but the inferences drawn by Sir Everard were equally 
ingenious and groundless. He supposed that the musi- 
cal ear was owing to the membrane of the tympanum.] 



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60 NATURAL THEOLOGY. 

principal property, that its use depends upon its. 
tension. Tension is the state essential to it. Now 
we know that, in a drum, the pelt is carried over 
a hoop, and braced as occasion requires, by the 
means of strings attached to its circumference. 
In the membrane of the ear, the same purpose is 
provided for, more simply, but not less mechani- 
cally nor less successfully, by a different expedient, 
viz. by the end of a bone (the handle of the mal- 
leus) pressing upon its centre. It is only in very 
large animals that the texture of this membrane 
can be discerned. In the Philosophical Transac- 
tions for the year 1800 (vol. i.), Mr. Everard 
Home has given some curious observations upon 
the ear, and the drum of the ear of an elephant. 
He discovered in it what he calls a radiated 
muscle — that is, straight muscular fibres passing 
along the membrane from the circumference to 
the centre — from the bony rim which surrounds it 
towards the handle of the malleus, to which the 
central part is attached. This muscle he sup- 
poses to be designed to bring the membrane into 
unison with different sounds; but then he also 
discovered, that this muscle itself cannot act, 
unless the membrane be drawn to a stretch, and 
kept in a due state of tightness, by what may be 
called a foreign force — ^viz. the action of the mus- 
cles of the malleus. Supposing his explanation of 



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NATURAL THEOLOGY. 61 

the use of the parts to be just, our author is well 
founded in the reflection which he makes upon 
it — " that this mode of adapting the ear to diffe- 
rent sounds, is one of the most beautiftil applica- 
tions of muscles in the body ; the mechanism is so 
simple, and the variety of effects so great.'' 

In another volume of the Transactions above re- 
ferred to, and of the same year, two most curious 
cases are related, of persons who retained the 
sense of hearing, not in a perfect but in a very 
considerable degree, notwithstanding the almost 
total loss of the membrane we have been de- 
scribing. In one of these cases, the use here 
assigned to that membrane, of modifying the im- 
pressions of sound by change of tension, was 
attempted to be supplied by straining the muscles 
of the outward ear. " The external ear," we are 
told, " had acquired a distinct motion upward and 
backward, which was observable whenever the 
patient listened to any thing which he did not 
distinctly hear; when he was addressed in a 
whisper, the ear was seen immediately to move ; 
when the tone of voice was louder, it then re- 
mained altogether motionless." 

It appears probable, from both these cases, 
that a collateral if not principal use of the mem- 
brane is to cover and protect the barrel of the 
ear which lies behind it. Both the patients suf- 



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62 KATURAL THEOLOGY. 

fered from cold : one, '* a great increase of deaf- 
ness from catching cold ;" the other, " very consi- 
derable pain from exposure to a stream of cold 
air." Bad effects therefore followed from this 
cavity being left open to the external air; yet, 
had the Author of Nature shut it up by any 
other cover than what was capable, by its texture, 
of receiving vibrations from sound, and, by its 
connexion with the interior parts, of transmitting 
those vibrations to the brain, the use of the organ, 
so far as we can judge, must have been entirely 
obstructed. 



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63 



CHAPTER IV. 

ON THE SUCCESSION OF PLANTS AND ANIMALS. 

The generoiion of the animal no more accounts 
for the contrivance of the eye or ear, than, upon 
the supposition stated in a preceding chapter, the 
production of a watch by the motion and mecha- 
nism of a former watch, would account for the 
skill and attention evidenced in the watch so pro- 
duced — than it would account for the disposition 
of the wheels, the catching of then* teeth, the re- 
lation of the several parts of the works to one 
another, and to their common end; for the suita- 
bleness of their forms and places to their offices, 
for their connexion, their operation, and the usefiil 
residt of that operation. I do insist most stre- 
nuously upon the correctness of this comparison ; 
that it holds as to every mode of specific propa- 
gation ; and that whatever was true of the watch, 
under the hypothesis above mentioned, is true of 
plants and animals. 

I. To begin with the fructification of plants. 
Can it be doubted but that the seed contains a 
particular organization ? Whether a latent plan- 
tule with the means of temporary nutrition, or 



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64 NATURAL THEOLOGY. 

whatever else it be, it encloses an organization 
suited to the germination of a new plant. Has 
the plant which produced the seed any thing 
more to do with that organization, than the watch 
would have had to do with the structure of the 
watch which was produced in the course of its 
mechanical movement ? I mean — Has it any 
thing at all to do with the contrivance? The 
maker and contriver of one watch, when he in- 
serted within it a mechanism suited to the pro- 
duction of another watch, was, in truth, the maker 
and contriver of that other watch. All the pro-, 
perties of the new watch were to be referred to 
his agency : the design manifested in it, to his in- 
tention : the art, to him as the artist : the collo- 
cation of each part, to his placing: the action, 
eflFect, and use, to his counsel, intelligence, and 
workmanship. In producing it by the interven- 
tion of a former watch, he was only working by 
one set of tools instead of another. So it is with 
the plant, and the seed produced by it. Can any 
distinction be assigned between the two cases; 
between the producing watch, and the producing 
plant; both passive unconscious substances; both, 
by the organization which was given to them, pro- 
ducing their like, without understanding or de- 
sign ; both, that is, instruments ? 

II. From plants we may proceed to oviparous 



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NATURAL THEOLOGY. 65 

animals : from seeds to eggs. Now I say, that 
the bird has the same concern in the formation of 
the egg which she lays, as the plant has in that 
of the seed which it drops ; and no other nor 
greater. The internal constitution of the egg is 
as much a secret to the hen as if the hen were 
inanimate. Her will cannot alter it, or change a 
single feather of the chick. She can neither 
foresee nor determine of Mjhich sex her brood sh^U 
be, or how many of either; yet the thing pro- 
duced shall be, from the first, very different in its 
make according to the sex which it bears. So 
far, therefore, from adapting the means, she is not 
beforehand apprised of the effect. If there be 
concealed within that smooth shell a provision 
and a preparation for the production and nourish- 
ment of a new animal, they are not of her pro- 
viding or preparing ; if there be contrivance, it is 
none of hers. Although, therefore, there be the 
difEerence of life and perceptivity between the 
animal and plant, it is a difference which enters 
not into the account; — it is a foreign circum- 
stance; it is a difference of properties not em- 
ployed. The animal function and the vegetable 
function are alike destitute of any design which 
can operate upon the form of the thing produced. 
The plant has no design in producing the seed — 
no comprehension of the nature or use of what it 



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66 NATURAL THEOLOGY. 

produces : the bird, with respect to its egg, is not 
above the plant with respect to its seed. Neither 
the one nor the other bears that sort of rehition 
to what proceeds from them which a joiner does 
to the chair which he makes. Now a cause which 
bears this relation to the effect, is what we want, 
in order to account for the suitableness of means 
to an end — the fitness and fitting of one thing to 
another ; and this cause the parent plant or ani- 
mal does not supply. 

It is further observable concerning the propa- 
gation of plants and animals, that the apparatus 
employed exhibits no resemblance to the thing 
produced; in this respect, holding an analogy 
with instruments and tools of art. The filaments, 
antherae, and stigmata of flowers, bear no more 
resemblance to the young plant, or even to the 
seed which is formed by their intervention, than 
a chisel or a plane does to a table or chair. What 
then are the filaments^ antherae> and stigmata of 
plants but instruments strictly so called? 

III. We may advance fi*om animals which bring 
forth eggs to animals which bring forth their 
young alive; and of this latter class, from the 
lowest to the highest ; from irrational to rational 
life, from brutes to the human species; without 
perceiving, as we proceed, any alteration whatever 
in the terms of the comparison. The rational 



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NATURAL THECMX>GY. 67 

animal does not produce its offspring with more 
certainty or success than the irrational animal: 
a man than a quadruped^ a quadruped than a 
bird ; nor (for we may follow the gradation through 
its whole scale) a bird than a plant; nor a plant 
than a watch^ a piece of dead mechanism, would 
do^ upon the supposition which has aheady so 
often been repeated. Bationality, therefore, has 
nothing to do in the business. If an account 
must be given of the contrivance which we ob- 
serve ; if it be demanded, whence arose either the 
contrivance by which the young animal is pro- 
duced, or the contrivance manifested in the young 
animal itself, it is not from the reason of the 
parent that any such account can be drawn. He 
is the cause of his offipring, in the same sense as 
that in which a gardener is the cause of the tulip 
which grows upon his parterre, and in no other. 
We admire the flower ; we examine the plant ; we 
perceive the conduciveness of many of its parts to 
their end and office : we observe a provision for 
its nourishment, growth, protection, and fecun- 
dity ; but we never think of the gardener in all 
this. We attribute nothing of this to his agency; 
yet it may still be true, that without the gardener 
we should not have had the tulip. Just so it is 
with the succession of animals, even of the highest 
order. For the contrivance discovered in the 



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68 NATURAL THEOLOGY. 

structure of the thing produced, we want a con- 
triver. The parent is not that contriver: his 
consciousness decides that question. He is in 
total ignorance why that which is produced took 
its present form rather than any other. It is for 
him only to be astonished by the effect. We can. 
no more look therefore to the intelligence of the 
parent animal for what we are in search of — a 
cause of relation, and of subserviency of parts to 
their use, which relation and subserviency we see 
in the procreated body — than we can refer the 
internal conformation of an acorn to the intelli- 
gence of the oak from which it dropped, or the 
structure of the watch to the intelligence of the, 
watch which produced it : there being no diffe- 
rence, as far as argument is concerned, between 
an intelligence which is not exerted, and an intel- 
ligence which does not exist." 

" When we have, in some measure, comprehended 
the system of an animal body, how the dififerent organs 
are related to each other, and how the whole exists 
through a mutual influence of its parts, the wonder is 
renewed how another creature should grow out of that, 
whicli, as far as we have seen, has no tendency to mul- 
tiply itself. Authors who treat of reproduction, even to 
the very last, affirm, that with the germ of life in all 
organized structures are conjoined the seeds of decay 
and of death : they tell us that the powers of life are 



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NATURAL THEOLOGY. 69 

finite, and that the time must come when they shall he 
expended. Now there are no seeds of decay; and 
although, according to the law of animal existence, the 
individual perishes, it is incorrect to say that it is the 
result of the exhaustion of the powers of vitality, or the 
deterioration of the material which enters into its com- 
position. We gain nothing hy adapting the language of 
one science to explain another : it is of no advantage, 
in treating of life and death, to adopt a chemical no- 
menclature. The term of Hfe in every creature, from 
the elephant to the ephemeral fly, has its limit ; hut it 
is wrong to say that it is hy the defect of the material, 
or of the energy of life : it is a hetter philosophy to 
admit that it is in accordance with the system which 
the Deity has ordained. 

Life, in the sense in which it is used here, is con- 
tinued in the germ that rises from the parent ; since out 
of the old body, that is described as a deteriorated and 
useless material, a new creation is produced, it suffices 
to show that there is' no necessary decay from the mate- 
rial itself. A leaf or twig of an old tree will strike root 
into the ground, and vegetate and exhibit youthful 
vigour. So -will the fresh-water polypus frirnish a por- 
tion which, being cut off, will grow with a perfect re- 
semblance to the original stock. In the reproduction 
of the higher and the more complex organized bodies 
there is much that is obscure; but in the tsimpler, and, 
as it is termed, the lower examples— vegetables, zoo- 
phytes, and infusory animals^— we have abundant proofs 



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70 NATURAL THEOLOGY. 

that the result does not proceed from the exhausted or 
deteriorated nature of the material. 

Amongst the infusoria, the animals called Monads^ 
of which there is a great variety, exhihit very curious 
phenomena. They are of a globular form, and this 
globe is seen first to contract and then divide, each 
becoming a distinct animal. And something like this 
may be done artificially by the division of the fresh- 
water polypus, or hydra ; and what is deficient in the 
divided portion is supplied by a new growth, be it head 
or tail. The thing, however, is not so remarkable, if 
we consider that those lower animals have abundant 
resemblance to vegetables ; and that in cutting off por- 
tions the experimenter is cutting off buds. These buds 
or tubercles, if left to undergo their natural changes, ac- 
quire independent motion, produce tentacula, or feelers, 
to procure food, and, thus prepared to be independent, 
fall off from the parent stock. 

The microscope exhibits another instance in the 
Volvox. It is a transparent globule, within which 
smaller globules may be seen ; and when matured the 
parent bursts, discloses the o£fepring, and dies. 

In all these examples, we see that there is no reason 
to speak of exhausted or deteriorated matter, or debility 
in the powers of life. 

So in the higher and the more complex animals we 
find one set of organs decaying and another rising into 
existence. Ck)ntemplating the one, we would say that 
the powers were decaying ; contemplating the other, that 



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NATURAL THEOLOGY. 71 

they were iresh and vigorous. We must come to the 
conclusion, then, that the growth of parts, or the period 
of their development, the decay of the animal, or of 
the parts of the animal, is by an ordinance which is 
very inaccurately expressed by the terms exhaustion of 
life, or imperfection of the material. Imperfection, in 
truth, is a relative term, and means failure or insuffi- 
ciency towards the accomplishment of certain purposes. 
If the object in view were the duration of animal bodies 
for a great length of time, we might be justified in say- 
ing that the materials they are made of are imperfect ; 
but this is clearly not the design with which they are 
formed. 



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72 NATURAL THEOLOGY. 



CHAPTER V. 

APPLICATION OF THE ARGUMENT CONTINUED. 

Every observation which was made in our first 
chapter concerning the watch, may be repeated 
with strict propriety concerning the eye ; concern- 
ing animals ; concerning plants ; concerning, in- 
deed, all the organized parts of the works of 
nature. As, 

I. When we are inquiring simply after the 
existence of an intelligent Creator, imperfection, 
inaccuracy, liability to disorder, occasional irregu- 
larities, may subsist in a considerable degree, 
without inducing any doubt into the question : 
just as a watch may frequently go wrong, seldom 
perhaps exactly right, may be faulty in some 
parts, defective in some, without the smallest 
ground of suspicion from thence arising that it 
was not a watch, not made, or not made for the 
purpose ascribed to it. When faults are pointed 
out, and when a question is started concerning 
the skill of the artist, or dexterity vnih. which the 
work is executed, then, indeed, in order to defend 
these qualities from accusation, we must be able. 



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NATURAL THEOLOGY. 73 

either to expose some intractablehess and imper- 
fection in the materials, or point out some invin- 
cible difficulty in the execution, into which imper.- 
fection and difficulty the matter of complaint may 
be resolved ; or, if we cannot do this, we must 
adduce such specimens of consummate art and 
contrivance proceeding from the same hand as 
may convince the inquirer of the existence, in the 
case before him, of impediments like those which 
we have mentioned, although, what from the na- 
ture of the case is very likely to happen, they be 
unknown and unperceived by him. This we must 
do in order to vindicate the artist's skill, or at 
least the perfection of it ; as we must also judge 
of his intention, and of the provisions employed 
in fiilfiUing that intention, not from an instance 
in which they fail, but from the great plurality of 
instances in which they succeed. But, after all, 
these are different questions from the question of 
the artist's existence ; or, which is the same, whe- 
ther the thing before us be a work of art or not ; 
and the questions ought always to be kept sepa- 
rate in the mind. So likewise it is in the works 
of nature. Irregularities and imperfections are 
of little or no weight in the consideration, when 
that consideration relates simply to the existence 
of a Creator* When the argument respects his 
attributes, they are of weight ; but are then to be 

K 



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74 NATURAL theologfy: 

taken in conjunction (the attention is not to rest 
upon them^ but they axe to be taken in conjunc- 
tion) with the unexceptionable evidences which 
we possess of skill, power> and benevolence, dis- 
played in other instances ; which evidences may, 
in strength, number, and variety, be such, and 
may so overpower apparent blemishes, as to in- 
duce us, upon the most reasonable ground, to 
believe that these last ought to be referred to 
some cause, though we be ignorant of it, otlier 
than defect of knowledge or of benevolence in the 
author. 

II. There may be also parts of plants and ani- 
mals, as there were supposed to be of the watch> 
of which^ in some instances the operation, in 
oUiers, the use, is unknown. These form different 
cases; for the operation may be unknown, yet 
the use be certain. Thus it is with* die lungs of 
animals. It does not, I think, appear, ihat we 
are acquainted with the action of the air upon the 
blood, or in what manner that action is communi- 
cated by the limgs ; yet we find that a very short 
suspension of their office destroys the life of the 
aainiar^. In this case, therefore, we may be said 

^ Undoubtedly the exposure of the blood to the atmo* 
^here, in Uiet^ircufadon through the lungs, and the throw-* 
vag off of carbon^ are essential to life. But the pain and 



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NATURAL THEOLOGY. tS 

taknow the use, nay, we experience thenecessity/ 
<i£the organ, though we be ignorant of its operas 
lion. Nearly flie same thing may be observed of 
what is called the lymphatic system. We suffer 
gfrievous incom^niences from its disorder, without 
l>ehig informed of the ofBce which it sustains in* 
tte economy of our bodies^ There may possibly 
alio be some few examples of the second class, in 
whiiA not only the operation is imknown, but in- 
^»hich experiments may seem to prove that the^ 
part is not necessary ; or may leave a doubt how^ 
fer it is even useful to the plant or animal in which' 
it is fouttd. This is said to be the case with the^ 
spdeen, which has been extracted from dogs with^ 
out any sensible injury to their vital ftmctions. 
Instances of the former kind, namely, in which we* 
cannot explain the- operation, may be numerous ;. 
fort they will be so in proportion to our ignorance.- 
They will be more or fewar to different persons, and^ 
in different stages of science. Every improvement' 
of knowledge diminishes their number. There 
IB hardly, perhaps, a year passes that does not, 
in- Ae woi^ of nature, bring some operation, or 



alarm excited when there is danger of suffocation are not 
so uiucli ff direct consequence of the interruption of tHe 
frmctionv a» an inrtance oTtlie manner in wbicfe the sen- 
flitnMtjfE^is bestowed to guard lihe important actio™ o€l$fe. 

e2 



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76 NATURAL THEOLOGY. 

some mode of operation^ to light, which was before 
xindiscovered — ^probably unsuspected. Instances 
of the second kind^ namely, where the part ap- 
pears to be totally useless, I believe to be ex-^ 
tremely rare ; compared with the number of those 
of which the use is evident, they are beneath any 
assignable proportion, and perhaps have been 
never submitted to a trial and examination suffi- 
ciently accurate, long enough continued, or often 
enough repeated. No accounts which I have seen 
are satis&ctory. The mutilated animal may live 
and grow fat (as was the case of the dog deprived 
of its spleen), yet may be defective in some other 
of its functions, which, whether they can all, or in 
what degree of vigour and perfection, be per- 
formed, or how long preserved without the extir- 
pated organ, does not seem to be ascertained by 
experiment. But to this case, even were it fully 
made out, may be applied the consideration which 
we suggested concerning the watch, viz., that 
these superfluous parts do not negative the rea- 
soning which we instituted concerning those parts 
which are useful, and of which we know the use ; 
the indication of contrivance, with respect to them, 
remains as it was before*', 

^^ In the higher animals there is a great complication 
of organs* Yet, in the lower animals, the functions of 



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NATURAL THEOLOGT, 77 

III. One atheistic way of replying to our ob- 
servations upon the works of nature^ and to the 
proofs of a Deity which we think that we per- 
ceive in them> is to tell us, that all which we see 
must necessarily have had some form, and that it 
might as well be its present form as any other. 
Let us now apply this answer to the eye, as we 
did before to the watch. Something or other 
must have occupied that place in the animal's 

digestion, respiration, assimilation, secretion, and growth 
proceed by means of an apparatus comparatively simple* 
We must not be surprised, then, that certain parts may 
be removed from the higher animals without destroying 
life. But this does not imply that those parts are use-* 
lessy since they are structures superadded for the finer 
adjustment of the different functions one to the other| 
belonging to a higher condition of the economy. 

With regard to parts which are thus called useless^ 
we must remember that the varieties of created ani- 
mals belong to one type. As we have just said, the 
essential functions are the same in all; and there is 
much of the structure common to all : when an ani- 
mal of a particular class has its organization adjusted to 
a certain condition of existence, we may see the rudi- 
ments of parts which, not being in action, are imperfect, 
and we must look to the individuals of another spe- 
cies or variety to discover them in their full deve- 
lopment. 



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78 JCATURAL THEOLOGY, 

h^d; mtiBt have filled up, we wiU say, that 
SQoket : we will say, ako, that it must hav^ been 
of that sort of mibatanoe which we leatll animal 
substance, as flesh, ibone, membrane, or cartilage^ 
&c. But that it should have been an eye, know* 
mg as we do what .an eye comprehends, — -viz. 
that it should have consisted, first, of a series of 
transparent lenses (very different, by^the^by, even 
in their substance, .from the opaque materials of 
which the rest of the body is, in general at least, 
pomposed; and with which the whole of its sur- 
fac9, this single portion of it excepted, is co- 
vered) : secondly, of a black cloth or canvass (the 
only membrane of the body which is black) spread 
out behind these lenses, so as to receive the 
image formed by pencils of light transmitted 
through them ; and placed at the precise georae^ 
trical distance, at which, and at which alone, a 
distinct image could be fi>rmefl, namely, at the 
concourse of the refracted rays : thirdly, of a 
large nerve communicating between this mem- 
brane and the brain; without which, the action 
of hght upon the membrane, however modified 
by the organ, would be lost to the purposes of 
sensation : — that this fortunate conformation of 
parts should have been the lot, .not of one indi- 
vidual out of many thousand individuals, like the 
great prize in a lottery, or like some singularity 



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NATURAIi THROLQCFY. 79 

in nature^ but the lia^ppy chaiice of a wliole ispe* 
<ues.: nor of one species out of many -thousand 
species^ with in^ch we are .a£quainted> but of by 
far the greatest number of all that exi^^ and 
that undco* varieties^ not casual or capricious^ but 
bearing .marks of being suited to their respective 
exigences.: — thai all this should have taken place, 
merely because something must have occupied 
these points on every animal's forehead; — or, 
that all this should be thqught to be accoimted 
for by the short answer, '^that whatever was 
there must have had some form or other/' is too 
absurd to be made more so by any augmentation. 
We are not contented with this answer ; we find 
iio satisffuction in it, by way of accounting for ap- 
pearances of organization far short of those of the 
iCye, such as we observe in fossil shells, petrified 
bones, or other substances which bear the vestiges 
of animal or vegetable recrements, but which, 
either in respect to utility, or of the situation in 
which they are discovered, may seem accidental 
enough. It is no way of accounting even for 
these things, to say, that the stone, for instance, 
which is shown to us (supposing the question to 
be concerning a petrification), must have contained 
some internal conformation or other. Nor does 
it mend the answer to add, with respect to the 
singularity of the conformation, that after the 



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80 NATURAL THEOLOOT. 

events it is no longer to be computed what the 
chances were against it. This is always to be 
computed when the question is, whether a usefiil 
or imitative conformation be the produce of 
chance or not : I desire no greater certainty in 
reasoning than that by which chance is excluded 
from the present <£sposition of the natural world. 
Universal experience is against it. What does 
chance ever do for us ? In the human body, for 
instance, chance, i. e. the operation of causes 
without design, may produce a wen, a wart, a 
mole, a pimple, but never an eye. Amongst 
inanimate substances, a clod, a pebble, a liquid 
drop might be ; but never was a watch, a tele- 
scope, an organised body of any kind, answering 
a valuable purpose by a complicated mechanism, 
the effect of chance**. In no assignable instance 

" There is great inaccuracy, and indeed a very unphi- 
losophical and superficial view of the subject in these 
obser^^ations upon " chance" Chance is merely an 
abridged form of expressing our ignorance of the cause or 
preceding event to which any given event may be traced ; 
and nothing can be more inaccurate, or indeed more 
productive of serious errors in this very branch of science, 
than to speak of chance as a substantive thing or power. 
To take the most obvious instance : we say, in common 
parlance, that the dice being shaken together, it is a 



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NATURAL THEOLOGT. 81 

liatli such a thing existed without intention some- 
where. 

matter of chance what faces they will turn up ; but, if we 
could accurately observe their position in the box before 
the shaking, the direction of the force appUed, its 
quantity, the number of turns of the box, and the 
curve in which the motion was made, the manner of 
stopping the motion and the line in which the dice 
were thrown out, the faces tmmed up would be a mat- 
ter of certain prediction, after a sufficient number of 
experiments had been made to correct the theory. It 
is only because we take no heed of all these things that 
we are ignorant what will be the event; and the dark- 
ness in which we are respecting the circumstances which 
regulate it, is called by the name of chance. Nor is it 
correct to say, that this or anything else is done without 
design. All we can mean by the expression is, that 
our design stops short at a certain point, and leaves the 
laws of nature to guide the rest of the operation. But 
such a position is manifestly quite inapplicable to the 
operations of nature. 

Equally inaccurate is it, if not more so, to speak of a 
wen or a pimple, &c., as the result of any cause in the 
least degree different from that which produced the eye. 
These are possibly always, certainly sometimes, diseases ; 
but they are the result of contrivance as clearly as the 
eye itself. The functions of the animal system, though 
acting in an imusual manner, yet acting according to 
rule, produce those phenomena. Indeed one of them, a 

b3 



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^gmmvm^mm 



82 If ATURAI. THEOLOGY. 

> IV. There k .another answer which has the 
same effect as the resolving of things into chance; 
which answer would persuade us to believe, -that 
the eye, the animal i;o which it belongs, every 
other animal, every plant, indeed every organized 
body which we see, are only so many x)ut of the 
possible varieties and combinations of being 
which the lapse of infinite ages has brought into 
existence; that the present world is the relic of 
that variety ; millions of other bodily forms and 
ether species having perished, being, by the .de- 
fect of their constitution, incapable of preserva- 
tion, or of continuance by generation. I^owihere 
is no foundation whatever for this conjecture in 
any thing which we observe in the works ofiia- 
ture ; no such experiments are going on at pre- 
sent; no such energy operates as that which is 
here supposed, and which should be constantly 
pushing into existence new varieties of beings. 

pimple, is, in part at least, the result of the provision 
made for restoring the interrupted continuity of the flkin, 
by a slight suppuration from which the granulation, or 
production of new animal fibre, takes place. The like 
remark apphes to the cases of a clad, pebble, or liquid 
drop, also put in this passage. We have already ad- 
verted to the two first in a fi)rmer note ; the formation 
of a drop is in truth one of the phenomena of gravita- 
tion, and a very remarkable one. 



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NATUHAL THEOLOGY. 83 

Nor are there any appearances to support an 
opinion^ that every possible combination of Tege- 
taUe or animal structure has formerly been tried. 
Multitudes of conformations, both of vegetables 
and animals, may be conceived capable of exist- 
ence and succession, which yet do not exist. Per- 
haps almost as many forms of plants might have 
been found in the fields as .figures of plants can 
be delineated upon paper. A countless variety 
of animals might have existed which do not exist. 
IJpon the supposition here stated, we should see 
unicorns and mermaids, sylphs and centaurs, the 
fancies of painters, and the fieibles of poets, realised 
by examples. Or, if it be alfeged that these may 
transgress the bounds of possible life and propa- 
gation, we might at least have nations of human 
beings without nails upon their fingers, with more 
or fewer fingers and toes than ten, some with one 
eye, others with one ear, with one nostril, or with- 
out the sense of smelling at all. All these, and 
a thousand other imaginable varieties, might hve 
and propagate. We may modify any one species 
many different ways, aU consistent with life, 
and with the actions necessary to preservation, 
althoygh affording different degrees of conve- 
niency and enjoyment to the animal. And if we 
carry these modifications through the different 
species which are known io subsist, their number 
would be incalculable. No reason can be given 



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84 NATURAL THEOLOGY, 

vihy, if these deperdits ever existed, they have 
now disappeared. Yet, if all possible existences 
have been tried, they must have formed part of 
the catalogue** . 

* No doubt men in different ages have asserted the 
possibility of all we see being made by chance ; but we 
are not uncharitable when we say that no man ever 
believed it. It is easily shown, that, of all the varieties 
of fabulous animals which have been bred in the fertile 
imagination of the poet, not one could have lived. They 
want that relation and balance of the different ox^ans, 
that provision running through the whole texture of the 
frame of the animal, which we see in the natural pro- 
ductions. The sphinx has wings, but no constitution 
of body to give these strength. The griffin, with its 
hooked bill, has 'no feathers to prin, and no substitute 
for teeth. The centaur has the body of the horse, but 
no mouth to gather appropriate food. 

We may conclude, then, that these products of the 
imagination are altogether abortive, and only tend to 
prove how exact the relation must be of all the parts, 
and especially of the vital organs of an animal, in order 
that it may live. 

As to the second position, that the animals which 
exist are the happy results of chance when thousands 
have perished by imperfection, the supposition is con- 
tradicted by the perfect and harmonious chain of beings 
forming the animal kingdom, in which there is no link 
interrupted, no interval implying the loss of any species. 



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NATURAL THEOLOGY. 85 

But, moreover, the division of organised sub* 
stances into animals and vegetables, and the dis* 
tribution and sub-distribution of each into genera 
and species, which distribution is not an arbitrary 
act of the mind, but founded in the order which 
prevails in external nature, appear to me to con- 
tradict the supposition of the present world being 
the remains of an indefinite variety of existences ; 
of a variety which rejects all plan. The hypo- 
thesis teaches, that every possible variety of being 
hath, at one time or other, found its way into 
existence (by what cause or in what manner is 
not said), and that those which were badly formed 
perished ; but how or why those which survived 
should be cast, as wc see that plants and animals 
are cast, into regular classes, the hypothesis does 
not explain ; or rather the hypothesis is inconsis- 
tent with this phenomenon. 

The hypothesis, indeed, is hardly deserving of 
the consideration which we have given to it, 
Wliat should we think of a man who, because we 
had never ourselves seen watches, telescopes, 
stocking-mills, steam-engines, &c., made, knew 
not how they were made, nor could prove by tes- 
timony when they were made, or by whom, would 
have us believe that these machines, instead of 
deriving their curious structures from the thought 
and design of their inventors and contrivers, in 



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86 STAfFURAL THBOLOG¥. 

truth denve tfaem from nd^aAeTtrngmi^hanitfais : 
viz., that a mass of metals and other materiak 
having run^ whenmelted^ into all possible figmt^s, 
and combined themselTes in all possible forms, 
and shapes, and proportions, ihese things vfbick 
we see are what were left from the accident, as 
best worth preserving, and, as such, are become 
the remaining stock of a magazine, which, at one 
time or other, has by this means contained every 
mechanism, useM and useless, convenient and 
inconvenient, into which such lik» materials could 
be thrown ? I cannot distinguish the hypothesis, 
as applied to the works of nature, from this solu- 
tion, which no one would accept as applied to a 
collection of machines. 

V, To the marks of contrivance discoverable in 
animal bodies, and to the argument deduced from 
them in proof of design and of a designing 'Crea- 
tor, this turn is sometimes attempted to be given, 
namely, that the parte were not intended for the 
use, but that the use arose out of the parts. This 
distinction is intelligible. A cabinet-maker rubs 
his mahogany with fish- skin; yet it would be too 
much to assert that the skin of the dog-fish was 
made rough and granulated on purpose for the 
polishing of wood, and the use of cabinet-makers. 
Therefore the distinction is inteUigible. Sut I 
think that there is very little place for itin:lhe 



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JTA-TURAL THEDLOar. 87 

mtdis ;Qf nalupe. Wkea joundly and general^ 
nffiimed vof ahem, as it Jiath sometimes been> it 
juaounis to suidi another Btretch of assertion as it 
ftould be to say, 4;hat all the implements of the 
iHibmet^mak^r's wtnrkshop, fUB >wdl as his fish^ 
dkin, were substance accidentally configurated, 
^hich he had picked up and converted to his use ; 
that his adzes, saws, planes, and gimlets, were not 
ipade, as we suppose, to hew, cut, smooth, shape 
out, or bore wood witb; but that, ^these things 
h^ng made, mo jottdtter with what design, or whe* 
tibieff with .any, the cabinett-maker perceived that 
ihey w^re tapplicable to his purpose, .and turned 
thiem.to account. 

•But, Again. So far as this solution is attempted 
to be applied to those .parts of animals the action 
of which does ndt depend upon the wiU of the 
animal, it is ftaught with still more evident ab- 
suifdity. Is it possible to believe that the eye 
was formed vrithout any regard to vidion; that 
it was the animal itsetf which found out that, 
though formed with no such intention, it would 
serve to see vnth; and that the use of the eye as 
an organ of sight resulted j&rom this discovery, 
and the animal's application of it? The same 
question may be asked of the ear; the same of 
all the senses. None of the senses fundamentally 
depend upon the election of the animal; conse- 



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88 NATURAL THEOLOGY. 

quently neither upon his sagacity nor his expe* 
rience. It is the impression 'which objects make 
upon them that constitutes their use. Under that 
impression he is passive. He may bring objects 
to the sense> or within its reach ; he may select 
these objects; but over the impression itself he 
has no power, or very little ; and that properly is 
the sense. 

Secondly ; there are many parts of animal bo- 
dies which seem to depend upon the will of the 
animal in a greater degree than the senses ^o> 
and yet with respect to which this solution id 
equally unsatisfactory. If we apply the solution 
to the human body, for instance, it forms itself 
into questions upon which no reasonable mind 
can doubt ; such as, whether the teeth were made 
expressly for the mastication of food, the feet for 
walking, the hands for holding ? or whether, these 
things being as they are, being in fact in the ani- 
mal's possession, his own ingenuity taught him 
that they were convertible to these purposes, 
though no such purposes were contemplated in 
their formation ? 

All that there is of the appearance of reason in 
this way of considering the subject is, that, in some 
cases, the organization seems to determine the 
habits of the animal, and its choice to a particular 
mode of life ; which, in a certain sense, may be 



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NATURAL THEOLOGY, 89 

called '' the use arising out of the part**." Now, 
to all the instances in which there is any place for 
this suggestion, it may he repUed, that the organ- 
ization determines the animal to habits beneficial 
and salutary to itself; and that this effect would 
not be seen so regularly to follow, if the several 
organizations did not bear a concerted and con- 
trived relation to the substance by which the ani- 

** We deceive ourselves in this matter : the dexterity 
which use gives, makes us apt to believe that the faculty 
is gained through the accidental possession of the instru- 
ment. But the difficulty is removed, if we make due 
comparison between man and other animals. In the 
former, it is intended that the faculty should be gradually 
developed; and the slowness with which perfection is 
attained leaves us in some doubt of the relation between 
the effort and the instrument used. But in the latter, 
all obscurity is removed : their propensities and instincts, 
and the use of their instruments are so perfect from the 
beginning, as to admit of no improvement. The fly- 
catcher requires no experience to adjust his eye, no 
second effort of his bill to correct the first. Whether it 
be the horn, or the tooth, or the sting, the disposition is 
given with it, and the mode of its action is prescribed. 
The spider weaves his web without improvement, or 
room for improvement. This subject is treated at some 
length in the " Bridgewater Treatise on the Hand," where 
the question is discussed, whether or not the possession 
of the hand is the source of man's superiority. 



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96 KATURAX THEOLOGY. 

jnal was strrrounded. They would^ otherwise, lae 
capacities without objects; powers without em- 
ployment. The web-&ot determinea, you «ay, ihe 
duck to swim ; but what would that avail if theze 
were no water to swim in ? The strong hooked 
bill and sharp talons of one species of bird deter- 
mine it to prey upon animals ; the soft straight 
biU and weak claws of another species determine 
it to pick up seeds : but neither rlef/^ rmiiiatmTi 
could take effect in providing for the sustenance 
of the birdi^, if-animal bodies and vegetable seeds 
did not lie within their reach. The pecuHar con- 
formation of the bill and tongue and claws of the 
woodpecker determines that bird to search for his 
food amongst the insects lodged behind the bark 
or in the wood of decayed trees; but what would 
this profit him if there were no trees, no decayed 
trees, no insects lodged under their bark, or in 
their trunk ? The proboscis with which the bee 
is fiirnished determines him to seek for honey : 
but what would that signify if flowers supplied 
none ? Faculties thrown down upon animals at 
random, and without reference to the objects 
amidst which they are placed, would not produce 
to them the services and benefits which we see : 
and if there be that referenqe, then there is in- 
tention. 

Xiastly ; the solution ^uls entirely when applied 
to plants. The. parts of plants answer their uses 



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^NAJ-UIUL THEOLOGY, 91 

without aBy coneuneiifie from the willor dicdce df 
the plant. 

VI. Others have dmsen itoxeferev^ery thing to 
a principle of order m natixre. A principle -at 
jDxder is the word: but what is meant .by a prin^ 
ciple of order, as different Aom an uartelligeBt 
Creator, has not been explained either bydefinir 
tion or example ; and, without such explanation, 
it should seem to be a mere substitution of words 
^r jreasons, names for eaufles. Order itself is 
only the adaptation of means to an end : a prin^ 
ciple of order, therefore, tjan only signify the mmd 
and intention which so adapts .them. Or, were it 
^capable of being explained in any other sense, is 
,there any experience, any analogy, to sustain it ? 
W;as a watch ever produced by a principle of 
order? and why might not awaiohbe so produced 
as well as an eye? 

' Eurtibtermoie, arpfinciple of ordBr,;acting bhndly 
and -without choice, is negatived by the observa- 
4ion that order is not universal; which it would 
ibe if it issued from a constant and necessary prin- 
.ciple : nor indiscriminate, which it would be if it 
issued from an unintelligent princaple. Wliere 
order is wanted, therie we -find it : where order is 
not wamted, i.e. where,if it prevailed, it would be 
useless, there we do not ^nd it. In the structure 
at' the eye (for we adhere to our example), in the 



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92 NATURAL THEOLOGY. 

figure and position of its several parts, the most 
exact order is maintained. In the forms of rocks 
and mountains, in the lines which bound the 
coasts of continents and islands, in the shape of 
bays and promontories, no order whatever is per- 
ceived, because it would have been superfluous. 
No useful purpose would have arisen from mould- 
ing rocks and mountains into regular solids, 
bounding the channel of the ocean by geometrical 
curves ; or from the map of the world resembling 
a table of diagrams in Euclid's Elements or 
Simpson's Conic Sections. 

VII. Lastly ; the confidence which we place in 
our observations upon the works of nature, in the 
inarks which we discover of contrivance, choice, 
and design, and in our reasoning upon the 
proofs afforded us, ought not to be shaken, as it 
is sometimes attempted to be done, by bringing 
forward to our view our own ignorance, or rather 
the general imperfection of our knowledge of 
nature. Nor, in many cases, ought this conside- 
ration to affect us, even when it respects some 
parts of the subject immediately under our notice. 
True fortitude of understanding consists in not 
suffering what we know to be disturbed by what 
we do not know. If we perceive a useful end, and 
means adapted to that end, we perceive enough 
for our conclusion. If these things be clear, no 



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NATURAL THEOLOGY. 93 

matter what is obscure. The argument is finished. 
For instance : if the utility of vision to the animal 
which enjoys it, and the adaptation of the eye to 
this oflSce, be evident and certain (and I can 
mention nothing which is more so), ought it to 
prejudice the inference which we draw from these 
premises, that we cannot explain the use of the 
spleen ? Nay, more : if there be parts of the eye, 
viz. the cornea, the crystalline, the retina, in their 
substance, figure, and position, manifestly suited 
to the formation of an image by the refraction of 
rays of light, at least as manifestly as the glasses 
and tubes of a dioptric telescope are suited to 
that purpose, it concerns not the proof which 
these afford of design, and of a designer, that 
there may perhaps be other parts, certain muscles, 
for instance, or nerves in the same eye, of the 
agency or effect of which we can give no accoimt, 
any more than we should be inclined to doubt, or 
ought to doubt, about the construction of a tele- 
scope, viz. for what purpose it was constructed, or 
whether it were constructed at all, because there 
belonged to it certain screws and pins, the use or 
action of which we did not comprehend. I take 
it to be a general way of inftising doubts and 
scruples into the mind, to recur to its own igno- 
rance, its own imbecility: to tell us that upon 
these subjects we know little ; that little imper- 



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94 NATURAL THEOLOGY. 

fectly ; or rather, that we know nothing prop^-ly 
about the matter. These suggestion* so fall' in 
with our consciousness as sometimes to produce 
a general distrust of our faculties and our ' con*^ 
elusions. But this is an unfounded jealonsy. 
The uncertainty of one thing does not necessarily 
afiect the certainty of another thing. Our igno- 
rance of many pomts need not suspend our as- 
surance of a fewv- Before we yield, in any parti-^ 
oular instajice, to the scepticiffln which this sort of 
insinuation would induce, we ought accurately to 
aacertsedn whether our ignorance or doubt concern^ 
l^ose precise points upon which owe conclusion 
Bests. Other points are nothing. Our ignorance- 
of other points may be of no consequence to* 
these, though they be points, in various respects, 
of great importance^ A just reasoner' removes 
fiom his consideration, not only what he- knows;^ 
but what he does not know, touching matters not'^ 
strictly connected with his arg^ment> ii ei not' 
forming the very steps of his deduction r beyond^ 
Ihesoi his knowledge aoid his ignorance are dike 
relative. 



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NATURAL THEOLOGY. 95 



CHAPTER VI. 

THE ARGUMENT CUMULATIVE. 

Were there no example in the world of con- 
trivance except that of the eye, it would be alone 
sufficient to support the conclusion which we draw 
from it, as to the necessity of an intelligent 
Creator. It could never be got rid of; because 
it could not be accounted for by any other sup- 
position, which did not contradict all the prin- 
eiples we possess of knowledge ; the principles 
according to which things do, as often as they 
can be brought to the test of experience, turn out 
to be true or &lse. Its coats and humours, con- 




[The figure iff introduced to remind the reader of the 
fine adjustment of the eye ;. a mibject explained in t^e 
Appendix: — A, B, is the object, and the lines represent^ 
Ae Hght reflected from it into the eye* On the surface 
of the cornea, which is the transparent part of the eye^ 



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96 NATURAL THEOLOGY. 

the rays are in a certain degree refracted. Passing 
through the coat called cornea, they enter the aqueous 
humour. In their transmission through it, they pass into 
the pupil. They enter the lens or crystalline humour, and 
by the greater power of refraction in this humour, the 
rays are drawn to* a point and impinge on the bottom of 
the eye at A, B. It will be further seen that the rays 
coming from B are refracted to a, those from A to 6, 
and that the image is therefore represented inverted.] 

structed as the lenses of a, telescope are con- 
structed, for the refraction of rays of light to a 
point, which forms the proper action of the organ ; 
the provision in its muscular tendons for turning 
its pupil to the object, similar to that which is 
given to the telescope by screws, and upon which 
power of direction in the eye the exercise of its 
office as an optical ' instrument depends ; the 
further provision for its defence, for its constant 
lubricity and moisture, which we see in its socket 
and its lids, in its glands for the secretion of the 
matter of tears, its outlet or communication with 
the nose for carrying off the liquid after the eye 
is washed with it ; these provisions compose alto- 
gether an apparatus, a system of parts, a prepa- 
ration of means, so manifest in their design, so 
exquisite in their contrivance, so successful in 
their issue, so precious, and so infinitely beneficial 
in their use, as, in my opinion, to bear down all 



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NATURAL THEOLOGY, 97 

doubt that can be raised upon the subject". 
And what I wish^ under the title of the present 
dtapter, to observe, is, that if other parts of 
nature were inaccessible to our inquiries, or even 
if other parts of nature presented^ nothing to our 
examination but disorder and concision, the va- 
lidity of this example would remain the same. If 
there were but one watch in the world, it would 
not be less certain that it had a maker. If we 
had never in our Ijves seen any but one single 
kind of hydraulic machine, yet, if of that one kind 
we understood the mechanism and use, we should 
be as perfectly assured that it proceeded from the 
hand and thought and skill of a workman, as if 
we visited a museum of the arts, and saw col- 
lected there twenty diflFerent kinds of machines 
for drawing water, or a thousand diflTerent kinds 
for other purposes. Of this point each machine 
is a proof independently of all the rest. So it is 
with the evidences of a Divine agency. The 
proof is not a conclusion which lies at the end of 
a chain of reasoning, of which chain each instance 
of contrivance is only a link, and of which, if one 
link fail, the whole falls ; but it is an argument 

** Again we have reference to the structure of the 
eye; which shows the necessity of throwing our ob- 
tervationB on this organ into the Appendix. 

F 



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98 NATURAL THEOLOGY. 

separately supplied by every separate example. 
An error in stating an e:^ample aflFects only that 
example. The argument is cumulative, in the 
fullest sense of that term. The eye proves it 
without the ear ; the ear without the eye. The 
proof in each example is complete ; for when the 
design of the part, and the conduciveness of its 
structure to that design is shown, the mind may 
set itself at rest; no future consideration can 
detract any thing from the force of the example. 



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NATURAL THEOLOGY* 99 



CHAPTER VII. 

OF THE MECHANICAL AND IMMECHANICAL PARTS AND 
FUNCTIONS OF ANIMALS AND VEGETABLES. 

It is not that every part of an animal or vegetable 
has not proceeded from a contriving mind; or 
that every part is not constructed with a view to 
its proper end and purpose, according to the lawa 
belonging to, and governing the substance or the 
action made use of in that part; or that each 
part is not so constructed as to eflFectuate its pur- 
pose whilst it operates according to these laws ; 
but it is because these laws tKemselves are not in 
all cases equally understood — or, what amounts 
to nearly the same thing, are not equally exem- 
plified in more simple processes, and more simple 
machines, that we lay down the distinction, here 
proposed, between the mechanical parts of ani- 
mals and vegetables.** 

*■ The observation here is most sensible. When we 
speak of an organ as peculiarly suited to exhibit design, 
we mean merely that we comprehend something of the 
object of the particular structure. But there is no part of 
an animal^ if we fully comprehended what was necessary 
to the performance of its functions, that would not raise 



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100 NATURAL THBOL06Y. 




[The reader will not be easily convinced that the mass 
of flesh, with which he is £Ekmiliar, i« easily and almost 
spontaneously divided into distinct mufleka* This figure 
represents a muscle. C is the belly of the muscle ; A 
and B the tendons : A being the tendinous origin^ as it is 
termed, attached to a fixed point of bone ; B the tendi- 
nous insertion, being attached to a part movable by the 
eontraction of the miwcle. The belly, C, eoiuists of 
fibres^ which are possessed of the power of eocEtraction 
or kritabiiity, and thiough the operaition of which the 
vmous metiona of the body are performed. We shall 
presently have to remark on the cUrection of these 
fibres.] • 

our admnution« Were we to take a portion of the skin, 
and contemplate its exquisite sensibility, so finely appro- 
priated — could we penetrate, as it were, into the pores, 
and duly estimate the power which regulates tixe secre- 
tions and absorption — could wc fully understand the 
relations of this organ, either with the economy of the 
body within^ or the constitution of the atmosphere with- 
out — ^we should have no occasion to draw our argument, 
for the twex^eth time, firom the structure of the eye or 
the ear. Were we to take one cell of the millions of that, 
substance which, intervening between the m«re solid 
textures of the frame, pvea diastic% to the wk^ Mid 



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NATURAL THEOLOOT. 101 



For instanee : the principle <^ mtmcular 
lion, viz., upon what cause the swelling of the 
belly of tl^ muscle, and ctftisequent contraction 
of its tendons, either by an act of the will, or bj 
involumtary irritation, depends, is wholly unknown 
to us. The substance employed^ whether it be 
fluid, gaseous, elastic, electrical, or none of these^ 
or nothing resembling these, is also imknown t» 
us : of course, the laws belonging to that sub^ 
stance, and which regulate its action, are unknown 
to us. We see nothing similar to this contrao 
tion in any machine which we can make, or any 
process which we can execute. So far (it is con* 
fessed) we are in ignorance, but no farther. This 
power and principle, from whatever cause it pro* 
ceeds, being assimied, the collocation of the fibres 
to receive the prmcijde, the disposition of the 
muscles for the use and application of the power, 
is mechanical; and is as intelligible as the ad* 
justment of the wires and strings by whidhi a 
puppet is moved. We see, therefore, as fer as 
respects the subject before us, what is not me- 
chanical in the animal frame, and what is. The 

permits circulation and muscular action, and all the 
various movements of the body, we should have in that 
one cell as much reason for wonder at the perfection of 
the contrivance, as in any joint of the limb. 



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102 J^ATURAL THEOLOGY. 

nervous influence (for we are often obliged to 
give names to things which we know little about) 
— I say the nervous •influence, by which the belly 
or middle of the muscle is swelled, is not mecha- 
nical. The utility of the effect we perceive — the 
means, or the preparation of means, by which it is 
produced, we do not. But obscurity as to the 
origin of muscular motion brings no doubtfulness 
into our observations, upon the sequel of the pro- 
cess : which observations relate — 1st, to the con- 
stitution of the muscle, in consequence of which 
constitution, the swelling of the belly or middle 
part is necessarily and mechanically followed by a 
contraction of the tendons; 2dly, to the number 
and variety of the muscles, and the corresponding 
number and variety of usefiil powers which they 
supply to the animal, which is astonishingly 
great ; 3dly, to the judicious (if we may be per* 
mitted to use that term in speaking of the 
Author, or of the works, of Nature), to the wise 
and well-contrived disposition of each muscle for 
its specific purpose ; for moving the joint this 
way, and that way, and the other way ; for pulling 
and drawing the part to which it is attached in a 
determinate and particular direction : which is a 
mechanical operation exemplified in d multitude 
of instances. To mention only one : The tendon 
of the trochlear muscle of the eye, to the end 



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NATURAL THEOLOGY. 103 

thai it may draw in the line required^ is passed 
through a cartilaginous ring, at which it is re- 
Verted^ exactly in the same manner as a rope in a 
ship is carried over a block, or round a stay, in 
order to make it pull in the direction which is 
wanted. All this, as we have said, is mechanical, 
and is as accessible to inspection, as capable of 
being ascertained, as the mechanism of the auto- 
maton in the Strand. Supposing the automaton 
to be put in motion by a magnet (which is pro- 
bable), it will supply us ^vitli a comparison very 
apt for our present purpose! Of the magnetic 
effluvium we know perhaps as little as we do of 
the nervous fluid. But, magnetic attraction being 
assumed (it signifies nothing from what cause it 
proceeds), we can trace, or there can be pointed 
out to us, with perf9ct clearness and certainty^ 
the mechanism, viz., the steel bars, the wheels, the 
joints, the wii'es, by which the motion so much 
admired is communicated to the fingers of the 
image ; and to make any obscurity, or difficulty, 
or controversy in the doctrine of magnetism, an 
objection to our knowledge or our certainty, 
concerning the contrivance, or the marks of con- 
trivance, displayed in the automaton, would be 
exactly the same thing as it is to make our igno- 
rance (which we acknowledge) of the cause of 
nervous agency, or even of the substance and 



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104 NATURAL THSOLOQT. 

stmeture of the nerves tiftemsehreB^ a giovsid of 
question or suspicion as to the reasoning nffaiek 
we institnte ooneeming Hie mechanical part of 
<mr frame. That an animal is a madune is a 
proposition neither correctly true nwr whoUy false. 
The distinction which we have been disoossi^ 
will serve to show how far the companson, whidi 
this expression implies^, holds; and ifd^rein it 
fails. And whether the distinction be though a£ 
importance or not, it is certainly erf importance to 
remember, that there is neither truth nor justice 
in endeavouring to bring a cloud over our under- 
standings, or a distrust into our reasonings upon 
this subject, by suggesting that we know nothmg 
-of voluntary motion, of instability, of the prindple 
of life, of sensation, of animal heat, upon all which 
the animal functions depend ; for, our ignorance 
of these parts of the animal frame concerns not at 
all our knowledge of the mechanical parts of the 
same frame. I contend, therefore, that there is 
mechanism in animals ; that this mechanism is as 
properly such, as it is in machines made by art ; 
that this mechanism is intelligible and certain ; 
4;hat it is not the less so, because it often begins 
t)r terminates with something which is not media- 
nical ; that whenever it is intelligible and certain 
it demonstrates intention and contrivance, as weH 
in the works of nature, as in those of art; and 



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NATUBAL THBOLOaY* X05 

that it is the best demonstration which either csm. 
afford. 

But whikt I contend for these prcqpositions^ I 
do not exclude myself from asserting, that there 
may be, and that there are, other cases in which, 
although we cannot exhibit mechanism, or prove 
indeed that mechanism is employed, we want not 
sufficient evidence to conduct us to the same con- 
clusion. 

There is what may be called the chemical part 
of our frame; of which, by reason of the imperfec- 
tion of our chemistry, we can attain to no distinct 
knowledge ; I mean, not to a knowledge, either in 
degree or kind, similar to that which we possess 
of the mechanical part of our frame. It does not, 
therefore, afford the same species of argument ae 
that which mechanism affords; and yet it may 
afford an argument in a high degree satisfactory. 
The gastric juice, or the liquor which digests the 
food in the stomachs of animals, is of this class. 
Of all the menstrua it is the most active, tne most 
universal. In the human stomach, for instance, 
consider what a variety of strange substances, and 
how widely different fi'om one another, it in a few 
hours reduces to a uniform pulp, milk, or muci- 
lage. It seizes upon everything ; it dissolves the 
texture of ahnost everything that comes in its way. 
The flesh of perhaps all animals ; the seeds and 

f3 



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106 NATURAL THEOLOGY. 

fruits of the greatest number of plants ; the roots, 
and stalks, and leaves of pany, hard and tough 
as they are, yield to its powerful pervasion. The 
change wrought by it is different from any che- 
mical solution which we can produce, or with 
which we are acquainted, in this respect as well as 
many others, that, in our chemistry, particular 
menstrua act only upon particular substances. 
Consider, moreover, that this fluid, stronger in its 
operation than a caustic alkali or mineral acid, 
than red precipitate, or aqua-fortis itself, is never- 
theless as mild, and bland, and inoffensive to the 
touch or taste as saliva or gum-water, which it 
much resembles. Consider, I say, these several 
properties of the digestive organ, and of the juice 
with which it is supplied, or rather with which it 
is made to supply itself, and you will confess it to 
be entitled to a name which it has sometimes 
received, that of " the chemical wonder of animal 
nature." 

Still we are ignorant of the composition of this 
fluid, and of the mode of its action ; by which is 
meant, that we are not capable, as we are in the 
mechanical part of our frame, of collating it with 
the operations of art. And this I call the imper- 
fection of our chemistry; for, should the time ever 
arrive, which is not, perhaps, to be despaired of, 
when we can compound ingredients so as to form 



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NATURAL THEOLOGY. 107 

a solvent which will act in the manner in which 
the gastric juice acts, we may be able to ascertain 
the chemical principles upon which its efficacy 
depends, as well as from what part, and by what 
concoction, in the human body these principles are 
generated and derived. 

In the mean time, ought that, which is in truth 
the defect of our chemistry, to hinder us from 
acquiescing in the inference which a production 
of nature, by its place, its properties, its action, its 
surprising efficacy, its invaluable use, authorizes 
us to draw in respect of a creative design**? 

Another most subtle and curious function of 
animal Ijodies is secretion. This function is semi- 



** After this enumeration of the things dissolved by 
the gastric juice, the most extraordinary fact remains to 
be stated, that the delicate surface of the stomach itself, 
softer and finer than the surface of the eye, remains 
untouched hv this humour, which our author, somewhat 
quaintly, describes as more powerful to dissolve than 
aqua-fortis. John Hunter showed us that it was the 
property of life that x*rotected the coate of the stomach. 
This fact is a most singular proof of the power bestowed 
through life on the membranes and vessels; and it is as 
unportant as it is curious : for as the stomach in the 
dead body no longer resists this mcnstruum,it may become 
dissolved, if the person has died with the fluid already 



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108 IJATURAL THEOLOGY. 

chemical and semi-mechanical; exceedingly im- 
portant and diversified in its effects, but obscure 
in its process and in its apparatus. The impor^ 
tance of the secretory organs is out too wdl 
attested by the diseases which an excessive, a de- 
ficient, or a vitiated secretion is almost sure of 
producing. A single secretion being wrong is 
enough to make life miserable, or sometimes to 
destroy it. Nor is the variety less than the im- 
portance. From one and the same blood (I speak 
of the human body) about twenty different fluids 
are separated; in their sensible properties^ in 
taste, smell, colour, and consistency, the most 
unlike one another that is possible ; thick, thii^ 
salt, bitter, sweet ; and if from our own we pass to 
other species of animals, we find amongst their 
secretions not only the most various but the most 
opposite properties ; the most nutritious aliment, 
the deadliest poison ; the sweetest perfiimes, the 
most foetid odours. Of these the greater part, as 
the gastric juice, the saliva, the bile, the slippery 
mucilage which lubricates the joints, the tears 

secreted into the stomach. And so it has happened that 
persons have been supposed to be poisoned, and rela- 
tions have been falsely accused, from the stomach being 
found eroded as if some acrid poison had been taken 
before death. 



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NATURAL THEOLOGY. 109 

which moisten the eye, the wax which defends the 
ear, are, after they are secreted, made use of in 
the animal economy, are evidently subservient, 
and are actually contributing to the utilities of 
the animal itself. Other fluids seem to be sepa- 
rated only to be rejected. That this also is neces- 
sary (though why it was originally necessary we 
cannot tell) is shown by the consequence erf the 
separation being long suspended, which conse- 
quence is disease and death. Akin to secretion, 
if not the same thing, is assimilation, by which one 
and the same blood is converted into bone, mus- 
cular flesh, nerves, membranes, tendons ; things 
as different as the wood and iron, canvass and 
cordage, of which a ship with its furniture is com- 
posed. We have no operation of art wherewith 
exactly to compare all this, for no other reason, 
perhaps, than that all operations of art are ex- 
ceeded by it. No chemical election, no chemical 
analysis or resolution of a substance into its con- 
stituent parts, no mechanical sifting or division 
that we are acquainted with, in perfection or va- 
riety come up to animal secretion. Nevertheless, 
the apparatus and process are obscure, not to say 
absolutely concealed from our inquiries. In a few 
and only a few instances, we can discern a little 
of the constitution of a gland. In the kidneys 
of large animals, we can trace the emulgent 



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110 NATURAL THEOLOGY. 

artery diriding itself into an hifinite number of 
branches ; their extremities every where commu- 
nicating with little round bodies, in the substance 
of which bodies the secret of the machinery 
seems to reside, for there the change is made. 
We can discern pipes laid from these round 
bodies towards the pelvis, which is a basin ^vithin 
the solid of the kidney. We can discern these 
pipes joining and collecting together into larger 
pipes; and, when so collected, ending in innu- 
merable papillae, through which the secreted fluid 
is continually oozing into its receptacle. This is 
all we know of the mechanism of a gland, even in 
the case in which it seems most capable of being 
investigated. Yet to pronounce that we know 
nothing of animal secretion, or nothing satisfac- 
torily, and with that concise remark to dismiss 
the article from our argument, would be to dis- 
pose of the subject very hastily and very irra- 
tionally. For the purpose which we want, that 
of evincing intention, we know a great deal. 
And what we know is this. We see the blood 
earned by a pipe, conduit, or duct, to the gland. 
We see an organised apparatus, be its construe- 
tion or action what it mil, which we call that 
gland. We see the blood, or part of the blood, 
after it has passed through and undergone the 
action of the gland, coming from it by an emul- 



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NATURAL THEOLOGY. Ill 

gent vein or artdry, i. e., by another pipe or con- 
duit. And we see also at the same time a new 
and specific fluid issuing from the same gland by 
its excretory duct, i, e., by a third pipe or conduit ; 
which new fluid is in some cases discharged out 
of the body, in more cases retained within it, and 
there executing some important and intelligent 
office. Now supposing, or admitting, that we 
know nothing of the proper internal constitution 
of a gland, or of the mode of its acting upon the 
blood, then our situation is precisely like that 
of an unmechanical looker-on, who stands by a 
stocking-lbom, a corn-mill, a carding-machine, or 
a thrashing-machine, at work, the fabric and 
mechanism of which, as well as all that passes 
within, is hidden from his sight by the outside 
case ; or, if seen, would be too complicated for 
his uninformed, uninstructed understanding to 
comprehend. And what is that situation ? This 
spectator, ignorant as he is, sees at one end a 
material enter the machine, as unground grain 
the miU, raw cotton the carding-machine, sheaves 
of unthrashed corn the thrashing-machine ; and, 
when he casts his eye to the other end of the 
apparatus, he sees the material issuing from it in 
a new state ; and, what is more, in a state mani- 
festly adapted to future uses ; the grain in meal 
fit for the making of bread, the wool in rovings 



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112 NATURAL THEOLOOT, 

ready for spinning into threads^ the sheaf in com 
dressed for the mill. Is it necessary Ihat this 
man^ in order to be convinced that design^ that 
intention^ that contrivance has been employed 
about the machine^ should be allowed to pull it 
to pieces; should be enabled to examine the 
parts separately ; explore their action upon one 
another^ or their operation, whether simultaneous 
or successive, upon the material which is pre- 
sented to them? He may long to do this to gratify 
his curiosity ; he may desire to do it to improve 
his theoretic knowledge ; or he may hare a more 
substantial reason for requesting it, if ke happen, 
instead of a common visitor, to be a millwright 
by profession, or a person sometimes called in to 
repair such-like machines when out of order; but 
for the purpose of ascertaining the existence of 
counsel and design in the formation of the ma- 
chine, he wants no such intromission or privity. 
What he sees is sufficient. The eflFect upon the 
material, the change produced in it, the utility of 
that change for future applications, abundantly 
testify, be the concealed part of the machine or 
of its construction what it will, the hand and 
agency of a contriver. 

If any confirmation were wanting to the evi- 
dence which the animal secretions afford of de- 
sign, it may be derived, as has been already 



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NATURAL THEOLOGY. 113 

fctffted, from their variety, and fiwm their appro- 
Pmtion to their place and use. They all omne 
Wtbe same blood; they are aU drawn off by 
gfends ; yet the produce is very Afferent, and the 
difference exactly adapted to the work which is to 
be done, or theend to be answered. Noaccoimt 
can be given of this, without resorting toappohrt> 
^t. Why, for instance, is the saUva, which is 
<Mftised over the seat of taste, insipid, whilst so 
many others of the secretions, the urine, the 
tears, and the sweat, are salt ? Why does the 
gland within the ear separate a viscid substance, 
which defends that passage; the gland in the 
iipper angle of the eye a thin brine, which washes 
the ball ? Why is the synovia of the joints muci- 
laginous ; the bile bitter, stimulating, and soapy ? 
Why does the juice which flows into the stomach 
contain powers which make that bowel the great 
laboratory, as it is by its situation the recipient, 
of the materials of future nutrition? These are 
all fair questions ; and no answer can be given 
to them but what calls in intelligence and in- 
tention. 

My object in tlie present chapter has been to 
teach three things : first, that it is a mistake to 
suppose that^ in reasoning from the appearances 
of nature, the inaperfection of our knowledge pro- 
portionably affects the certainty of our conclusion ; 



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114 >'ATURAL THEOLOGY. 

for in many cases it does not affect it at all: 
secondly, that the different parts of the animal 
frame may be classed and distributed according 
to the degree of exactness with which we compare 
them with works of art : thirdly, that the mecha- 
nical parts of our &ame^ or those in which this 
<x>mparison is most complete, although constitut- 
ing, probably, the coarsest portions of nature's 
workmanship, are the most proper to be alleged 
as proofs and specimens of design. 



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NATURAL THEOLOGY. 



115 



CHAPTER VIII. 

OF MECHANICAL ARRANGEMENT IN THE HUMAN 
FRAME. 




[This figure represents the lower surface or base of 
the skull. The hole is the foramen magnum through 
which the spinal marrow descends into the spine ; and 
on each side of the hole are the Articulating processes, 
called the condyles,'] 

We proceed, therefore, to propose certain exam- 
ples taken out of this class; making choice of 
such as, amongst those which have come to our 



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116 NATURAL THEOLOGY. 

knowledge, appear to be the most striking and 
the best understood; but obliged, perhaps, to 
postpone both these recommendations to a third : 
that of the example being capable of explanation 
without plates, or figures, or technical language. 

OF THE BONES. 

I. — I challenge asxjr mstm to produce in the 
joints and pivots of the most complicated or the 
'most flexible wrihiiie that -mm ewT contrived, a 
construction mose artifieial, or nere evidently ar- 
tificial, than that vUch is seen in Hie vertebrae of 
the human rmek. Tk© iiibigv were to be done : 
the head ym& to laame iS^ fower of bending for- 
ward and biK^waipd, as in tine act of nodding, 
stooping, looking upward or downward; and, at 
the same time, of turning itself rc»md upon the 
body to a certain extent — ^the ^jiiadrant, we will 
say, or rather, perhaps, a knudred- and -twenty 
degrees of a circle. For these two purposes, two 
distinct contrivances are employed : firat, the 
head rests immediately upon the uppermost part 
of the vertebrae, and is united to it by a Mnge- 
joint ; upon which joint the head plays •fredy for- 
ward and backward, as far either way as is ne- 
cessary, or as the ligaments aUow ; whkdi was the 
first thing required. But ihen the rotatory wm^ 
tion is unprovided for: therefore, secondly, to 



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NATURAL THECHiOOY. 117 




[Tliis fi gpw t rcjweseiite tlie ii|vycBnost vertebra, or 
atlas ; and theeondylei, mentioiDeil m the former figure, 
sink into the artseulatixig suxfnoea of tbnr vertebra, per- 
mitting the noddmg^ modooa. a snd b are the articu- 
lating surfaces ; c b a surfaee whk^ receives the tooth 
of the vertebra below ; d the ckck through which the 
spinal marrow panKa.] 

make the head capable of this, a fiirther mecha- 
nism is introduced: not between the head and 
the uppermost bone of the neck, where the hinge 
is, but between that bone and the bone next 
underneath it. It is a mechanism resembling a 
tcTwn and mortise. This second, or uppermost 
bone but one^ has what anatomists call a process, 
Tiz^ a projection, somewhat similar, in size and 
shape, to a tooth ; which tooth, entering a corre~ 
sponding hole or socket in the bone above it, forms 
a pivot or >axle, upon which that upper bone, 
together ^th the head which it supports, turns 
freely in a circle ; and as far in the circle as the 
attached muscles permit the head to turn. Thus 
are both motions perfect without interfering with 
each other. When we nod the head, we use the 



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118 NATURAL THEOLOGY. 

hinge-joint^ which lies between the head and the 
first bone of the neck. When we turn the head 
rounds we use the tenon and mortise, which runs 
between the first bone of the neck and the second.'* 




[Here the tooth-like process of the second vertebra^ 
which is called dentala, is passed through the ring of 
the first, and is held there by a transverse ligament, like 
a spindle in the bush. No doubt the object of this com- 
plexity is to permit the free motion of the head, without 
too great a laxity at any one joining, and thereby to pro- 
tect the most vital organ of the body, the medulla oh- 
longcUay or spinal marrow, which passes firom the head 
into the tube of the spine.] 

We see the same contrivance and the same prin- 
ciple employed in the frame or mounting of a tele- 

•* The meaning of our author is obvious here ; but 
the tenon and mortise are terms used for the firm joining 
of beams, as in the carpentry of a roof; not for rotatory 
motion. 



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NATURAL THEOLOGY. 119 

scope. It is occasionally requisite that the object- 
end of the instrument be moved up and down, as 
well as horizontally, or equatorially. For the 
vertical motion, there is a hinge, upon which the 
telescope plays ; for the horizontal or equatorial 
motion, an axis upon which the telescope and the 
hinge turn round together. And this is exactly 
the mechknism which is applied to the motion of 
the head ; nor will any one here doubt of the ex- 
istence of counsel and design, except it be by that 
debility of mind, which can trust to its own rea- 
sonings in nothing. 

We may add, that it was, on another account, 
also expedient that the motion of the head back- 
ward and forward should be performed upon the 
upper surface of the first vertebra; for, if the first 
vertebra itself had bent forwa:i^d, it would have 
brought the spinal marrow, at the very beginning 
of its course, upon the point of the tooth. 

II. Another mechanical contrivance, not unlike 
the last in its object, but different and original in 
its means, is seen in what anatomists call the 
fore-arm — that is, in the arm between the elbow 
and the vfrist. Here, for the perfect use of the 
hmb, two motions are wanted : a motion at the 
elbow, backward and forward, which is called a 
reciprocal motion; and a rotatory motion, by 
which the palm of the hand, as occasion requires. 



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120 



haturjll theology. 



may be turned upward. How is this managed ? 
The fore-arm, it is well known, consists of two 
bones, lying alongside each other, but touching 
only towards the ends. One,^ and only one, of 
these bones is joined to the cubit, or upper part 
of the arm^ at the elbow; the other alone to the 



[Since it has been our author's 
pleasure to take this instance, the 
figure will illustrate his description. 
A is the lower part of the arm-bone, 
or humerus; B is the ulna and C 
the radlusy the two bones of the fore- 
arm. It will be understood how these 
bones, being tied together by liga- 
ments, hinge and move upon the hu- 
merus A ; c being the process of the 
ulna, on which we rest when leaning 
on the elbow. By applying our hand 
to the arm, we at once feel the free- 
dom with which the bone moves in 
bending and extending the arm. — 
When we turn the key in a lock, or 
make the guards in fencing by the 
motion of the wrist, the ulna B is 
stationary, and the radius C turns 
round upon the head of the bone at d 
and e, carrying the hand with it. The 
rest is abundantly well explained in 
the text.] 



^ 



■^i 



s 



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KATURAL THEOLOGY. 121 

hand at the wrist. The first, by means, at the 
elbow, of a hinge-joint (which allows only of mo- 
tion in the same plane), swings backward and for- 
ward, carrying along with it the other bone, and 
the whole fore-arm. In the mean time, as often 
as there is occasion to turn the palm upward, 
that other bone to which the hand is attached 
rolls upon the first, by the help of a groove or 
hollow near each end of one bone, to which is 
fitted a corresponding prominence in the other. 
If both bones had been joined to the cubit, or 
upper arm, at the elbow, or both to the hand at 
the wrist, the thing could not have been done. 
The first was to be at liberty at one end, and the 
second at the other; by which means the twb 
actions may be performed together. The great 
bone which carries the fore-arm may be swinging 
upon its hinge at the elbow, at the very time that 
the lesser bone, which carries the hand, may be 
turning round it in the grooves. The manage-^ 
ment, also, of these grooves, or rather of the 
tubercles and grooves, is very observable. The 
two bones are called the radius and the ulna. 
Above, u e,, towards the elboW, a tubercle of the 
radius plays into a socket of the ulna; whilst 
below, i. e.> towards the wrist, the radius finds the 
socket, and the ulna the tubercle. A single bone 
in the fore-arm, with a ball-and-socket joint at the 



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122 NATURAL THEOLOGY. 

elbow, which admits of motion in all directions, 
might, in some degree, have answered the pur- 
pose of both moving the arm and turning the 
hand. But how much better it is accomplished 
by the present mechanism any person may con- 
vince himself who puts the ease and quickness 
with which he can shake his hand at the wrist cir- 
cularly (moving likewise, if he pleases, his arm at 
the elbow at the same time)' in competition with 
the comparatively slow and laborious motion with 
which his arm can be made to turn round at the 
shoulder by the aid of a baU and socket joint. 

III. The spine, or back-bone, is a chain of joints 
of very wonderful construction. Various, difficult, 
and almost inconsistent offices were to be executed 
by the same instrument. It was to be firm, yet 
flexible (now, I know no chain made by art which 
is both these ; for by firmness I mean, not only 
strength but stability) ; firm, to support the erect 
position of the body; flexible, to allow of the 
bending of the trunk in all degrees of curvature. 
It was further also (which is another and quite a 
distinct purpose from the rest) to become a pipe 
or conduit for the safe conveyance from the brain 
of the most important fluid of the animal frame, 
that, namely, upon which all voluntary motion 
depends, the spinal marrow ; a substance not only 
of the first necessity to action, if not to life, but 



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NATURAL THHlOLOOYt 123 

of a nature so delicate and tender, so susceptible 
and so impatient of injury, as that any unusual 
pressure upon it, or any considerable obstruction, 
of its course, is followed by paralysis or death. 




[This represents a section of three of the lower yerte* 
brae. The subject being by no means exhausted in the 
text, the reader will find it taken up in the Appendix.] 

Now the spine was not only to fiimish the main 
trunk for the passage of the medullary substance 
from the brain, but to give out, in the course of 
its progress, small pipes thorefrom, wbkh^ being 
afterwards indefinitely subdiTided, might, under 
the name of ttoires, distribiite this exquisite sup- 
ply to ercry part of the body. The same spbie 
was abo to senre anodiCT use not less wanted than 

g2 



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124 NATURAL THEOLOGY. 

the preceding, viz., to afford a fulcrum, stay, or 
basis (or, more i>roperly speaking, a series of 
ttiese) for the insertion of the muscles which are 
spread over the trunk of the body ; in which trunk 
there are not, as in the limbs, cylindrical bones 
to which they can be fastened : and likewise, which 
is a similar use, to furnish a support for the ends 
of the ribs to rest upon. 

Bespeak of a workman a piece of mechanism 
which shall comprise all these pui-poses, and let 
him set about to contrive it ; let him try his skill 
upon it ; let him feel the difficulty of accomplish- 
ing the task, before he be told how the same thing 
is effected in the animal frame. Nothing will 
enable him to judge so well of the wisdom which 
has been employed ; nothing will dispose him to 
think of it so truly. First, for the firmness, yet 
flexibility, of the spine ; it is composed of a great 
number of bones (in the human subject, of twenty* 
four) joined to one another, and compacted by 
broad bases. The breadth of the bases upon 
which the parts severally rest, and the closeness 
of the junction, give to the chain its firmness and 
stability ; the number of parts, and consequent 
frequency of joints, its flexibility. Which flexibi- 
lity, we may also observe, varies in different parts 
of the chain ; is least in the back, where strength 
more than flexure is wanted; greater in the loins. 



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KATURAL THEOLOGr, 125 

which it was necessary should be more supple than 
the back ; and greatest of aU in the neck, for th6 
free motion of the head. Then, secondly, m order 
to afford a passage for the descent of the medul- 
lary substance, each of these bones is bored 
through in the middle, in such a manner as that, 
when put together, the hole in one bone falls into 
a hne and corresponds with the holes in tlie two 
bones contiguous to it. By which means the per- 
forated pieces, when joined, form an entire, close, 
uninterrupted channel, at least while the spine is 
upright and at rest. But as a settled posture is 
inconsistent with its use, a great difficulty still 
remained, which was to prevent the vertebrse 
shifting upon one another, so as to break the Une 
of the canal as often as the body moves or twists, 
or the joints gaping externally whenever the body 
IS bent forward and the spine thereupon made to 
take the form of a bow. These dangers, which 
are mechanical, are mechanically provided against. 
The vertebrae, by means of their processes and 
projections, and of the articulations which some 
of these form with one another at their extremi- 
ties, are so locked in and confined as to maintain, 
m what are called the bodies or broad surfaces of 
the bones, the relative position nearly unaltered, 
and to throw the change and the pressure pro. 
duced by flexion almost entirely upon the inter- 



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126 NATURAL THEOLOGY. 

vening cartib^s^ the springiness and yielding 
nature of whose substance admits of all the mo- 
tion which is necessary to be performed upon 
thern^ without any chasm being produced by a 
separation of the parts. I say, of all the motion 
tvhich is necessary; for, although we bend our 
backs to every degree almost of inclination, the 
motion of each vertebra is very small : such is the 
advantage we receive from the chain being com- 
posed of so many hnks, the spine of so many 
bones. Had it consisted of three or four bones 
only, in bending the body the spinal marrow must 
have been bruised at every angle. The reader 
need not be told that these intervening cartilages 
are gristles, and he may see them in perfection in 
a loin of veal. Their form also favours the same 
intention. They are thicker before than behind ; 
so that, when we stoop forward, the compressible 
substance of the cartilage, yielding in its thicker 
and anterior part to the force which squeezes it, 
trings the surface of the adjoining vertebrae 
nearer to the being parallel with one anoth^ 
than they were before, instead of increasing the 
inclination of their planes, which must have occa- 
sioned a fissure or opening between them, 
llirdly, for the medullary canal giving out in 
its course, and in a convenient order, a supply of 
nerves to different parts of the body, notches are 



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NATURAL THBOLOOT. 127 

made in the upper and lower edge of every ver- 
tebra, two on each edge, equidistant on each side 
fipom the middle line of the back. When the 
vertebrae are put together, these notches, exactly 
fitting, form small holes, through which the 
nerves at each articulation issue out in pairs, in 
order to send their branches to every part of the 
body, and with an equal bounty to both sides of 
the body. The f(mrth purpose assigned to the 
same instrument is the insertion of the bases of the 
muscles, and the support of the ends of the ribs ; 
and for this fourth purpose, especially the former 
part of it, a figure, specifically suited to the de- 
sign, and unnecessary for the other purposes, is 
given to the constituent bones. Whilst they are 
plain, and round, and smooth towards the fronts 
where any roughness or projection might have 
wounded the adjacent viscera, they run out, be- 
hind, and on each side, into long processes, to 
which processes the muscles necessary to the mo- 
tions of the trunk are fixed, and fixed with such 
art, that, whilst the vertebrae supply a basis for 
the muscles, the muscles help to keep these bones 
in their position, or by their tendons to tie them 
together. 

That most important, however, and general 
property, viz., the strength of the compages, and 
the security against luxation, was to be still more 



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128 NATURAL THEOLOGY, 

specially consulted; for, where, so many joints 
were concerned, and where, in every one, derange- 
ment would have been fatal, it became a subject 
of studious precaution. For this purpose the 
vertebrae are articulated, that is, the moveable 
joints between them are formed by means of those 
projections of their substance which we have men- 
tioned under the name of processes, and these so 
lock in with and overwrap one another as to secure 
the body of the vertebra not only from accident- 
ally slipping, but even from being pushed out of 
its place by any violence short of that which would 
break the bone. I have often remarked and ad- 
mired this structure in the chine of a hare. In 
this, as in many instances, a plain observer of the 
animal economy may spare himself the disgust of 
being present at human dissections, and yet learn 
enough for his information and satisfaction, by 
even examining the bones of the animals which 
come upon his table. Let him take, for example, 
into his hands a piece of the clean-picked bone of 
a hare's back, consisting, we will suppose, of three 
vertebrae. He will find the middle bone of the 
three so imphcated, by means of its projections 
or processes, with the bone on each side of it, that 
tio pressure which he can use will force it out of 
its place between them. It vnll give way neither 
forward nor backward, nor on either side. In 



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NATURAL THEOLOGY.: 129 

wbichever direction he pushes, he perceives, in 
the form, or junction, or overlapping of the bones^ 
an impediment opposed to his attempt, a check and 
guard against dislocation . In one part of the spine 
he will find a still fiirther fortifying expedient> 
in the mode according to which the vertebrae are 
annexed to the spine. Each rib rests upon two 
vertebrae. That is the thing to be remarked, and 
any one may remark it in carving a neck of mut- 
ton. The manner of it is this : the end of the rib 
is divided by a middle ridge into two surfaces, 
whidb surfaces are joined to the bodies of two con- 
tiguous vertebrae, the ridge applying itself to the 
intervening cartilage. Now this is the very contri- 
vance which is employed in the famous iron bridge 
at my door at Bishop-Wearmouth, and for the same 
purpose of stability, viz., the cheeks of the bars 
which pass between the arches ride across the 
joints by which the pieces composing each arch 
are united. Each cross-bar rests upon two of 
these pieces at their place of junction, and by that 
position resists, at least in one direction, any ten- 
dency in either piece to slip out of its place. 
Thus perfectly, by one means or the other, is tlie 
danger of slipping laterally, or of being drawn 
aside out of the line of the back, provided against; 
and, to withstand the bones being pulled asunder 
longitudinally, or in the direction of that line, a 

G 3 



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130 NATURAL THEOLOGY. 

gtrong membrane runs from one end of the chain 
to the other^ sufficient to resist any force which is 
ever likely to act in the direction of the back or 
parallel to it, and consequently to secure the whole 
combination in their places. The general result 
is, that not only the motions of the human body 
necessary for the ordinary offices of life are per- 
fonned with safety, but that it is an accident 
hardly ever heard of that even the gesticulations 
of a harlequin distort his spine. 

Ujwn the whole, and as a guide to those who 
may be inclined to carry the consideration of this 
subject farther, there are three views under which 
the spine ought to be regarded, and in all which 
it cannot fail to excite our admiration. These 
views relate to its articulations, its ligaments, and 
its perforation ; and to the corresponding advan- 
tages which the body derives from it, for action, 
for strength, and for that which is essential to 
every part, a secure communication with the 
brain. 

The structure of the spine is not in general 
different in different animals.** In the serpent 

*• There is a notion entertained by the ingenious and 
somewhat fanciful physiologists of France, that the ex- 
tremities of the body, the parts furthest removed from 
the centre^ tore most subject to change in their conforma- 



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NATURAL THE(M.OOY. 131 

tribe, however, it is considerably varied; but 
with a strict reference to the conveniency of the 

tion, whilst the central parts of the system are the most 
unvarying. Entertaining such a view, we lose much of 
the interest that is attached to the subject; and the 
inference which it is important to draw is forgotten, 
the accommodation not of parts only, but of the whole 
framework of the animal body, to the peculiar condition 
or necessities of the creature. The teeth vary because 
the food is different ; the feet vary, because the mode of 
progression is different; the claws vary in connexion 
with the teeth, and the mode of procuring food, by 
digging, or scraping, or by holding and tearing. So does 
the eye, and so does the ear. But with these adaptations 
of parts, we must not lose sight of the fact which is the 
most important to our conclusions — that the whole is 
accommodated, as well as the individual organs. 

The spine in all vertebrated animals holds its office in 
perpetuity ; it contains and protects the spinal marrow ; 
and so far as its office is permanent, there will be an uni- 
formity in its appearance in all creatures. But even in 
man it varies in its structure, in the different portions or 
divisions of it, as these portions are required to admit of 
more or less freedom of motion. In the hare, as men- 
tioned in the text, the spine is beautifully accommodated 
to the motion in running. In the cat-kind, as the leopard 
or tiger, it has a lateral mobility, quite. different from: its 
structure in the horse or the stag. In the boar, the ver- 
tebrse are unusually firm, and the processes enormously 



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132 JIATURAL THEOLOGY; 

animaL For, whereas in quadrupeds the number 
of vertebrae is from thirty to forty, in the serpent 
it is nearly one hundred and fifty: whereas in 
men and quadrupeds the surfaces of the bones 
are flat, and these flat surfaces laid one against 
the other, and bound tight by sinews; in the 
serpent, the bones play one within another, like a 
ball and socket,* so that they have a free motion 
upon one another in every direction : that is to 
say, in men and quadrupeds, firmness is more 
consulted ; in serpents, pliancy. Yet even pliancy 
is not obtained at the expense of safety. The 
back-bone of a serpent, for coherence and flexi- 
bility, is one of the most curious pieces of animal 
mechanism with which we are acquainted. The 
chain of a watch (I mean the chain which passes 
between the spring-barrel and the fusee), which 
aims at the same properties, is but a bungling 
piece of workmanship in comparison with that of 
which we speak. 

extended, to give strength to the union with the head, 
and to direct the action of the muscles upon the head, 
80 that he may tear up strong roots and possess his de- 
fence in his powerful tusks. In short, as far as the 
spine is required to accommodate itself to the motions 
of the trunk, it is varied with as fine an adjustment as 
the furthest bone of the toe or finger. 

* Der. Phys. Theol p. 396. 



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NATURAL THEOLOGY> 133 

IV. The reciprocal enlargement and contrac- 
tion of the chest to allow for the play of the lungs, 
depends upon a simple yet beautiful mechanical 
contrivance, referable to the structure of the 
bones which enclose it. The ribs are articulated 
to the back-bone, or rather to its side projections, 
obliquely : that is, in their natural position they 
bend or slope from the place of articulation 
downwards. But the basis upon which they rest 
at this end being fixed, the consequence of the 
obKquity, or the inclination downwards, is, that 
when they come to move, whatever pulls the ribs 
upwards, necessarily, at the same time, draws 
them out; and that, whilst the ribs are brought 
to a right angle with the spine behind, the ster- 
num, or part of the chest to which they are 
attached in front, is thrust forward. The simple 
action, therefore, of the elevating muscles does 
the business ; whereas, if the ribs had been arti- 
culated with the bodies of the vertebrae at right 
angles, the cavity of the thorax could never have 
been further enlarged by a change of their posi- 
tion. If each rib had been a rigid bone, articu- 
culated at both ends to fixed bases, the whole 
chest had been immoveable. Keill has observed 
that the breast-bone, in an easy inspiration, is 
thrust out one-tenth of an inch ; and he calculates 
that this, added to what is gained to the space 



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134 NATURAL THEOLOGY. 

within the chest by the flattening or descent of 
the diaphragm, leaves room for forty-two cubic 
inches of air to enter at every drawing-in of the 
breath. When there is a necessity for a deeper 
and more laborious inspiration, the enlargement 
of the capacity of the chest may be so increased 
by effort, as that the lungs may be distended 
with seventy or a hundred such cubic inches.* 
The thoi^ax, says Schelhammer, forms a kind of 
bellows, such as never have been, nor probably 
will be, made by any artificer."'' 

V. The patella, or knee-pan, is a curious little 
bone: in its form and office unlike any other 
bone in the body. It is circular ; the size of a 
crown -piece 3 pretty thick; a little convex on 
both sides, and covered with a smooth cartilage. 
It lies upon the front of the knee : and the 
powerful tendons, by which the leg is brought 
forward, pass through it (or rather it makes a 
part of their continuation), from their origin in 
the thigh to their insertion in the tibia. It pro- 

^ In the dissertation in the Appendix on the Th(Mtuc, 
it will be observed that we have additional proofs of the 
accommodatioD of the bones of the trunk, as well as of 
the bones of the extremities, to the varying habits and 
condition of the animal. 

• Anat p. 229. 



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NATURAL THEOLOGY. 



135 



tects both the tendon and the joint from any 
injury which either might suffer, by tlie rubbing 
of one against the other, or by the pressure of 




[Three views of the kuee-joints.] 
unequal surfaces. It also gives to the tendons a 
very considerable mehanical advantage, by alter- 
ing the line of their direction, and by advancing 
it farther out from the centre of motion; and 
this upon the principles of the resolution of 
force, upon which principles all machinery is 
founded. These are its uses. But what is most 
observable in it is, that it appears to be supple- 
mental, as it were, to the frame: added, as it 
should almost seem, afterward; not quite neces- 
sary, but very convenient. It is separate from 
the other bones : that is, it is not connected with 
any other bones by the common mode of union. 
It is soft, or hardly formed, in infancy; and 
produced by an ossification, of the inception, or 



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136 NATURAL THEOLOGY. 

progress of which no account can be given from 
the structure or exercise of the part. 

VI. The ahoulder-blade is, in some material 
respects, a very singular bone : appearing to be 
made so expressly for its own purpose, and so 
independently of every other reason. In such 
quadrupeds as have no collar-bones, which are by 
far the greater number, the shoulder-blade has 
no bony communication with the trunk, either by 
a joint, or process, or in any other way. It does 
not grow to, or out of, any other bone of the 
trunk. It does not apply to any other bone of 
the trunk — (I know not whether this be true of 
any second bone in the body, except perhaps the 
OS hyoides) : in strictness, it forms no part of the 
skeleton. It is bedded in the flesh, attached only 
to the muscles. It is no other than a foundation 
bone for the arm, laid in, separate as it were, and 
distinct, from the general ossification. The lower 
limbs connect themselves at the hip with bones 
which form part of the skeleton ; but this con- 
nexion, in the upper limbs, being wanting, a 
basis, whereupon the arm might be articulated, 
wafi to be supplied by a detached ossification for 
the purpose." 

"^ The Bhoulder-blade undergoes many cbaDges, as 
we view it in comparative anatomy. That bone which 
we feel running across the upper part of the chest and 



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JJATURAL THEOLOGT. 137 

OF THE JOINTS. 

I. The above are a few examples of bones 
made remarkable by their configuration ; but to 

lower part of the neck, the collar-bone, is properly a 
process of the shoulder-blade. (See the figure in the 
Appendix, No. 7, c,c.) Its purpose is to hold the 
shoulders apart, and to give strength to the arms, by 
throwing upon the arm the action of the muscles of the 
chest. Accordingly, we find it in climbing animals, in 
those which require to swing themselves by the upper 
extremities, as the monkeys ; but in animals that have 
a solid hoof, which implies that the anterior extremity is 
for the particular purpose of running or bounding upon 
the ground, not only is there no occasion for that variety 
in the motions of the extremity, which is produced by the 
introduction of this bone into the skeleton of the arm, 
but it would be injurious — it would deprive the animal 
of that elasticity with which it alights upon the ground. 
Where there is no clavicle — in the horse and deer, for 
example, the shoulder-blade, or scapula, is attached to 
the trunk by muscles alone. Hence when the animal 
makes a leap, it comes down upon the fore-legs with an 
elastic rebound, the trunk hanging upon the muscles, 
the muscles supported by the scapula, and the scapula 
sustained upon the bones of the extremity. There is no 
solid substance to receive the shock. Were the collar- 
bone introduced here, it would be snapped across by the 
percussion, as happens to a man when he is thrown 
upon his shoulder. 



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138 NATURAL THEOLOGY. 

almost all the bones belong joints ; and in these^ 
still more clearly than in the form or shape of 
the bones themselves^ are seen both contrivance 
and contriving wisdom. Every joint is a cu- 
riosity, and is also strictly mechanical. There is 
the hinge-joint and the mortice-and- tenon joint; 
each as manifestly such, and as accurately de- 
fined, as any which can be produced out of a 
cabinet-maker's shop ; and one or the other 
prevails, as either is adapted to the motion which 
is wanted — e. g,, a mortice and tenon, or ball and 
socket joint, is not required at the knee, the leg 
standing in need only of a motion backward and 
forward in the same plane, for which a hinge- 
joint is sufficient; a mortice and tenon, or ball 
and socket joint, is wanted at the hip, that not 
only the progressive step may be provided for, 
but the interval between the limbs may be en- 
larged or contracted at pleasure. Now observe 
what would have been the inconveniency — i. e., 
both the superfluity and the defect of articu- 
lation, if the case had been inverted : if the ball 
and socket joint had been at the knee, and the 
hinge-joint at the hip. The thighs must have 
been kept constantly together, and the legs had 
been loose and straddling. There would have 
been no use, that we know of, in being able to 
turn the calves of the legs before; and there 



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NATURAL THEOLOGY. 139 

would have been great confinement by restrain- 
ing the motion of the thighs to one plane. The 
disadvantage would not have been less^ if the 
joints at the hip and the knee had been both of 
the same sort; both balls and sockets, or both 
hinges : yet why, independently of utility, and of 
a Creator who consulted that utility, should the 
same bone (the thigh-bone) be rounded at one 
end, and channelled at the other ? 

The hinge-joint is not formed by a bolt passing 
through the two parts of the hinge, and thus 
keeping them in their places, but by a difle- 
rent expedient. A strong, tough, parchment-like 
membrane, rising from the receiving bones, and 
inserted all round the received bones a little 
below their heads, encloses the joint on every 
side. This membrane ties, confines, and holds 
the ends of the bones together, keeping the 
corresponding parts of the joints — i, e., the rela- 
tive convexities and concavities — in close applica- 
tion to each other. 

For the ball and socket joint, beside the mem- 
brane already described, there is in some important 
joints, as an additional security, a short, strong, 
yet flexible ligament, inserted by one end into 
the head of the ball, by the other into the bottom 
of the cup, which ligament keeps the two parts of 
the joint so firmly in their place, that none of the 



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140 NATURAL THEOLOGY, 

motions which the limb naturally performs^ none 
of the jerks and twists to which it is ordinarily 
liable, nothing less indeed than the utmost and 
the most unnatural violence, can pull them asun- 
der. It is hardly imaginable, how great a force 
is necessary, even to stretch, still more to break* 
this ligament : yet so flexible is it, as to oppose 
no impediment to the suppleness of the joint. 
By its situation also it is inaccessible to injury 
from sharp edges. As it cannot be ruptured 
(such is its strength), so it cannot be cut, except 
by an accident which would sever the limb. If I 
liad been permitted to frame a proof of con- 
trivance, such as might satisfy the most dis- 
trustful inquirer, I know not whether I could 
have chosen an example of mechanism more un- 
equivocal, or more free fi*om objection, than this 
ligament. Nothing can be more mechanical; 
nothing, however subservient to the safety, less 
capable of being generated by the action of the 
joint. I would particularly solicit the reader's 
attention to this provision, as it is found in the 
head of the thigh-bone : to its strength, its struc- 
ture, and its use. It is an instance upon which I 
lay my hand. One single fact, weighed by a 
mind in earnest, leaves oftentimes the deepest 
impression. For the purpose of addressing dif- 
ferent understandings and different apprehen- 



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NATURAL THEOLOOr, 141 

sions — for the purpose of sentiment — for the 
purpose of exciting admiration of the Creator's 
works, we diversify our views, we multiply our 
examples: but for the purpose of strict argu- 
ment, one clear instance is sufficient; and not 
only sufficient, but capable perhaps of generating 
a firmer assurance than what can arise from a 
divided attention.** 

The ginglymus, or hinge-joint, does not, it is 
manifest, admit of a ligament of the same kind 
with that of the ball and socket joint ; but it is 
always fortified by the species of ligament of 
which it does admit. The strong, firm, investing 
membrane, above described, accompanies it in 
every part; and in particular joints, this mem- 
brane, which is properly a ligament, is considera- 
bly stronger on the sides than either before or 
behind, in order that the convexities may play 
true in their concavities, and not be subject to 
sKp sideways, which is the chief danger; for the 
muscular tendons generally restrain the parts 



•• This ligament is absent in the orang-outang ; and 
in the lower extremity of this animal, there are other 
points of resemblance to the structure of the arm ; and 
certainly the use of the hinder extremity corresponds 
with this structure, since he grasps and swings equally 
well with either Extremity. 



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142 NATURAL THEOLOGY. 

from going farther than they ought to go in the 
plane of their motion. In the knee, which is a 
joint of this form, and of great importance, there 
are superadded to the common provisions for the 
stabiUty of the joint, two strong ligaments, which 
cross each other — and cross each other in such a 
manner, as to secure the joint from being dis- 
placed in any assignable direction. "I think," 
says Cheselden, "that the knee cannot be com- 
pletely dislocated without breaking the cross liga- 
ments."* We can hardly help comparing this 
with the binding up of a fracture, where the fillet 
is almost wholly strapped across, for the sake of 
giving firmness and strength to the bandage. 

Another no less important joint, and that also 
of the ginglymus sort, is the ankle ; yet though 
important (in order, perhaps, to preserve the 
symmetry and lightness of the limb), small, and, 
on that account, more liable to injury. Now this 
joint is strengthened — i. <?., is defended from dis- 
location, by two remarkable processes or pro- 
longations of the bones of the leg, which processes 
form the protuberances that we call the inner 
and outer ankle. It is part of each bone going 
down lower than the other part, and thereby 
overlapping the joint : so that if the joint be in 
danger of slipping outward, it is curbed by the 
* Ches. Anat. ed. 7tb, p. 45. 



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NATURAL THEOLOGY. 143 

inner projection — i. e,, that of the tibia ; if in- 
ward; by the outer projection — i, e., that of the 
fibula. Between both, it is locked in its posi- 
tion. I know no account that can be given of 
this structure^ except its utility."** Why slK>uld 
the tibia terminate, at its lower extremity, with a 
double end, and the fibula the same — ^but to bar- 
ricade the joint on both sides by a continuation 
of part of the thickest of the bone over it ? The 
joint at the shoulder^ compared with the joint at 
the hip, though both ball and socket joints, dis- 
covers a difference in their form and proportions, 

^ It is surprising, that among so many instances our 
author should omit to notice the perfection in the ankle- 
joint. When we stand resting upon the foot, the joint 
is firm, and yields neither to the inside nor the outside; 
but when we move the foot forward and point the toe in 
making the step, such is the happy form of the hones 
that the foot is in this position thrown quite loose. The 
object here certainly is, that in walking on the irregular 
ground, we may have a freedom in directing the foot so 
as to plant it securely. But before the weight of the 
body is brought perpendicularly over the foot, there is 
no danger to the joint, because there is no strain upon 
it. Just in proportion as the advancing body begins to 
bear upon it do the bones take that position, in which 
they are as firm as in the knee-jdnt itself, admitting only 
the motion of a hinge. 



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144 NATURAL THEOLOGY. 

well suited to the different offices which the limbs 
have to execute. The cup or socket at the shoul- 
der is much shallower and flatter than it is at the 
hip, and is also in part formed of cartilage set 
round the rim of the cup. The socket, into which 
the head of the thigh-bone is inserted, is deeper, 
and made of more solid materials. This agreed 
with the duties assigned to each part. The 
arm is an instrument of motion, principally, if 
not solely. Accordingly, the shallowness of the 
socket at the shoulder, and the yieldingness of 
the cartilaginous substance with which its edge is 
set round, and which in fact composes a consider- 
able part of its concavity, are excellently adapted 
for the allowance of a free motion and a Avide 
range, both which the arm wants. Whereas, the 
lower limb, forming a part of the colimin of the 
body — having to support the body, as well as to 
be the means of its locomotion-i-firmness was to 
be consulted as well as action. With a capacity 
for motion, in all directions indeed, as at the 
shoulder, but not in any direction to the same 
extent as in the arm, was to be united stability^ 
or resistance to dislocation. Hence the deeper 
excavation of the socket, and the presence of A 
less proportion of cartilage upon the ^dge. 

The suppleness and pliability of the joints we 
every moment experience; and the firmness of 



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NATURAL THEOLOGY. 145 

animal articulation, the property we have hitherto 
been considering, may be judged of from this 
single observation, that, at any given moment of 
time, there are millions of animal joints in com- 
plete repair and use, for one that is dislocated; 
and this, notwithstanding the contortions and 
wrenches to which the limbs of animals are con- 
tinually subject. 

II. The joints, or rather the ends of the bones 
which form them, display also, in their configura- 
tion, another use. The nerves, blood-vessels, 
and tendons, which are necessary to the life, or 
for the motion, of the limbs, must, it is evident, 
in their way from the trunk of the body to the 
place of their destination, travel over the mov- 
able joints; and it is no less evident that, in 
this part of their course, they will have, from 
sudden motions, and from abrupt changes of cur- 
vature, to encoimter the danger of compression, 
attrition, or laceration. To guard fibres so ten- 
der against consequences so injurious, their path 
is in those parts protected with peculiar care; 
and that by a provision in the figure of the bones 
themselves. The nerves which supply the fare- 
army especially the inferior cubital nerves, are at 
the elbow conducted, by a kind of covered way, 
between the condyls, or rather under the inner 
extuberances of the bone which composes the 



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146 NATURAL THEOLOGY. 

upper paxt of the arm.* At the knee, the ex- 
tremity of the thigh-bone i» divided by a sinus^ 
or cliff, into two heads or protuberances; and 
these heads on the back-part stand out beyond 
the cylinder of the bone. Through the hollow 
which lies between the hind-parts of these two 
heads — that is to say, under the ham, between 
the ham-strings, and within the concave recess of 
the bone formed by the extuberances on each 
side — in a word, along a defile, between rocks, 
pass the great vessels and nerves which go to the 
leg.t Who led these vessels by a road so de- 
fended and secured ? In the joint at the shoulder, 
in the edge of the cup which receives the head of 
the bone, is a notch, which is joined or covered 
at the top with a ligament. Through this hole, 
thus guarded, the blood-vessels steal to their 
destination in the arm, instead of moimting over 
the edge of the concavity. J 

III. In all joints, the end of the bones, which 
work against each other, are tipped with gristle. 
In the ball and socket joint, the cup is lined and 
the ball capped with it. The smooth surface, the 
elastic and unfriable nature of cartilage, render it 
of all substances the most proper for the place 
and purpose. I should, therefore, have pointed 

* Ches.Anut.p. 255,6(1.7. 
t Ibia. p. 35. I IbW. p. 30. 



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NATURAL THEOLOGY. 147 

this out amongst the foremost of the provisions 
which have been made in the joints for the faci- 
litating of their action, had it not been alleged, 
that cartilage in truth is only nascent or imper- 
fect ix>ne; and that the bone in these places is 
kept soft and imperfect, in consequence of a more 
complete and rigid ossification being prevented 
from taking place by the continual motion and 
rubbing of the surfaces : which being so, what we 
represent as a designed advantage is an im- 
avoidable effect. I am far from being convinced 
that this is a true account of the fact ; or that, if 
it were so, it answers the argument.^^ To me 

*^ As the Archdeacon had been a pupil of Dr. William 
Hunter's, which we gather from the tenor of many of his 
observations, it is surprising that he has not spoken with 
more decision upon this point. The cartilage, which is 
the substitute for the bone in infancy, is very different 
from that which tips the ends of the articulating extre- 
mities of the bones. In a valuable paper of Dr. Hunter's, 
it is shown that this articulating cartilage consists of 
fibres, placed together like the hairs of a brush, but 
more compactly, and perpendicularly to the ends of the 
bones; and that on this arrangement chiefly depends 
the elasticity of the material. Its use is best proved^by 
what takes place when it is deficient : for then the arti- 
culation creaks like an old hinge, and the patient suffers 
aches. 

H 2 



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148 NATURAL THEOLOGY. 

the surmounting of the bones with gristle looks 
more like a plating with a different metal^ than 
like the same metal kept in a different state by 
the action to which it is exposed. At all events, 
we have a great particular benefit^ though arising 
from a general constitution; but this last, not 
"being quite what my argument requires, lest I 
should seem by applying the instance to over- 
rate its value, I have thought it fair to state the 
question which attends it. 

IV. In some joints, very particularly in the 
Ttnees, there are loose cartilages or gristles be- 
tween the bones, and within the joint, so that the 
«nds of the bones, instead of working upon one 
another, work upon the intermediate cartilages. 
Cheselden has observed*, that the contrivance of 
a loose ring is practised by mechanics where the 
friction of the joints of any of their machines is 
great, as between the parts of crook-hinges of 
large gates, or under the head of the male screw 
of large vices. The cartilages of which we speak 
have very much of the form of these rings. The 
comparison, moreover, shows the reason why we 
find them in the knees rather than in other joints. 
It is an expedient, we have seen, which a mechanic 
rdsorts to only when some strong and heavy work 

♦ Ches. Anat p. 13, ed. 7. 



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NATURAL THEOLOGY. 149 

is to be done. So Here the thigh-bone has to 
achieve its motion at the knee, with the whole 
weight of the body pressing upon it, and often, as 
in rising from our seat, with the whole weight of 
the body to lift. It should seem also, from Che- 
selden's account, that the shpping and sUding of 
the loose cartilages, though it be probably a small 
and obscure, change, humoured the motion at the 
end of the thigh-bone, under the particular confi- 
guration which was necessary to be given to it for 
the commodious action of the tendons (and 
which configuration requires what he calls a vari- 
able socket, that is, a concavity, the lines of which 
assume a different curvature in different incUna- 
tions of the bones*). 

^* This is not explained with our author's usual clear- 
ness. The lower head of the thigh-bone, which rests 
upon the shin-bone or tibiay is not the segment of a 
regular circle. When we stand with the knees straight, 
the thigh-bone rests with a broad surface, and the con- 
vexity is principally on the back part. Such an irregula- 
rity would make a very imperfect and jarring hinge-joint 
on any configuration that could be given to the correspond- 
ing surface of the tibia. Therefore these cartilages inter- 
vene; and, being possessed of considerable elasticity, 
and 80 connected with the bone as to shift their place a 
Httle, they accommodate themselves, whether the flatter 
end or the more convex part of the articulating surface 



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150 NATURAL THEOLOGY. 

V. We have now done with the configuration : 
but there is also in the joints^ and that cconmon 
to them all^ another ^exquisite proyision manifestly 
adapted to their use, and concerning which there 
can, I think, be no dispute, namely, the regular 
supply of a mucilage, more emoUient and slippery 
than oil itself, which is constantly softening and 
lubricating the parts that rub upon each other, 
and thereby diminishing the efiect of attrition in 
the highest possible degree. For the continual 
secretion of this important liniment, and for the 
feeding of the cavities of the joint with it, glands 
are fixed near each joint, the excretory ducts of 
which glands, dripping with their balsamic con- 
tents, hang loose like fringes within the cavity of 
the joints. A late improvement in what are called 
friction wheels, which consist of a mechanism so 
ordered as to be regularly dropping oil into a box 
which encloses the axis, the nave, and certain 
balls upon which the nave revolves, may be said, 
in some sort, to represent the contrivance in the 
animal joint, with this superiority, however, on 

of the bone be presented to them ; and there is this 
advantage, that, in standing, when the weight on the joint 
is greatest, the thigh-bone has a more extensive, and con- 
sequently a more secure basis, at the same time that the 
motion of the joint as a hinge is perfect. 



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NATURAL THEOLOGY. 151 

the part of the joint, viz., that here the oil is not 
only dropped, but made. 

In considering the joints, there is nothing, per- 
haps, which ought to move our gratitude more 
than the reflection, how well they wecer, A limb 
shall swing upon its hinge, or play in its socket, 
many hundred times in an hour, for sixty years 
together, without diminution of its agility, whidi 
is a long, time for anything to last — ^for anything 
so much worked and exercised as the joints are. 
This durability I should attribute in part to the 
provision which is made for the preventing of wear 
and tear, first, by the polish of the cartilaginous 
surfaces ; secondly, by the healing lubrication of 
the mucilage, and, in part, to that astonishing 
property of animal constitutions, assimilation, by 
which, in every portion of the body, let it consist 
of what it will, substance is restored, and waste 
repaired'®. 

•® This subject is touched upon in the Appendix, in 
treating of the spine. We may here take a practical 
illustration. We have said that exercise is necessary to 
the perfection of a joint Suppose the knee-joint to be 
inflamed : it is of course kept in perfect rest, because 
motion produces pain. This absolute rest, joined with 
inflammation, alters all the textures ; the bone becomes 
light and spongy ; the cartilage is absorbed ; the liga- 



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152 NATURAL THEOLOGY. 

Movable joints, I think, compose the curiosity 
of bones ; but their union, even where no motion 
is intended or wanted, carries marks of mechanism 
and of mechanical wisdom. • The teeth, especially 
the front teeth, are one bone fixed in another, 
like a peg driven into a board. The sutures of 
the skull are like the edges of two saws clapped 
together in such a manner as that the teeth of 
one enter the intervals of the other. We have 

ments which ought to hold the bones together become 
loose and relaxed; and what the surgeon calls consecu- 
tive dislocation may take place — that is, the bones will 
actually shift their place, from the defect of those attach- 
ments which ought to keep them together. Now, let us 
suppose the inflammation to have subsided : by due at- 
tention all may be restored ; and by no other mode than 
moving the joint — the only precaution necessary being, 
that it shall be moved with a care and gentleness corre- 
sponding to its weakened condition. By this simple 
means the ligaments will acquire firmness, the cartilages 
smoothness, and the synovia^ or lubricating mucilage, will 
be again poured out : from all which we see, that in the 
living animal textures, wear and tear do not take place 
upon continued motion ; but, on the contrary, that exer- 
cise is made the stimulus to improvement. All other 
proofs of design, as adjustment, relation, compensation," 
prospective contrivance, are weak in comparison with 
this. 



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NATURAL THEOLOGY. 153 

sometimes one bone lapping over another, and 
planed down at the edges; sometimes also the 
thin lamella of one bone received into a narrow 
fiirrow of another. In all which varieties we 
seem to discover the same design, viz., firmness of 
juncture without clumsiness in the seam. 



h3 



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154 NATURAL THEOLOGY. 



CHAPTER IX. 



OF THE MUSCLES. 



Muscles, with their tendons, are the instruments 
by which animal motion is performed. It will be 
our business to point out instances in which, and 
properties with respect to which, the disposition 
of these muscles is as strictly mechanical as that 
of the wires and strings of a puppet. 

I. We may observe, what I believe is univer- 
sal, an exact relation between the joint and the 
muscles which move it. Whatever motion the 
joint, by its mechanical construction, is capable of 
performing, that motion the annexed muscles, by 
their position, are capable of producing. For 
example, if there be, as at the knee and elbow, a 
hinge-joint, capable of motion only in the same 
plane, the leaders, as they are called, i.e., the 
muscular tendons, are placed in directions parallel 
to the bone, so as, by the contraction or relaxa- 
tion of the muscles to which they belong, to pro- 
duce that motion and no other. If these joints 
were capable of a freer motion, there are no 



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NATURAL THEOLOGY. 155 

muscles to produce it Whereas, at the shoulder 
and the hip, where the ball and socket joint al- 
lows by its construction of a rotatory or sweeping 
motion, tendons are placed in such a position, and. 
pull in such a direction, as to produce the motion 
of which the joint admits. For instance, the sar- 
torius or tailor's muscle, rising from the spine, 
running diagonally across the thigh, and taking 
hold of the inside of the main bone of the leg a 
little below the knee, enables us, by its contrac- 
tion, to throw one leg and thigh over the other, 
giving effect, at the same time, to the ball and 
socket joint at the hip, and the hinge-joint at the 
knee. There is, as we have seen, a specific me- 
chanism in the bones for the rotatory motions of 
the head and hands : there is, also, in the oblique 
direction of the muscles belonging to them, a 
specific provision for the putting of this mechan- 
ism of the bones into action. And mark the con- 
sent of uses : the oblique muscles would have been 
inefficient without that particular articulation; 
that particular articulation would have been lost 
without the obUque muscles. It may be proper, 
however, to observe, with respect to the head, al- 
though I think it does not vary the case, that its 
obUque motions and inclinations are often mo- 
tions in a diagonal produced by the joint action 
of muscles lying in straight directions. But 



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156 NATURAL THEOLOGY. 

whether the pull be single or combined, the 
articulation is always such as to be capable of 
obeying the action of the muscles. The oblique 
muscles attached to the head are likewise so dis- 
posed as to be capable of steadying the globe as 
well as of moving it. The head of a new-bom 
infant is often obliged to be filleted up. After 
death the head drops and rolls in every direction. 
So that it is by the equilibre of the muscles, by 
the aid of a considerable and equipollent muscu- 
lar force in constant exertion, that the head main- 
tains its erect posture. The muscles here supply 
what would otherwise be a great defect in the 
articulation; for the joint in the neck, although 
admirably adapted to the motion of the head, is 
insufficient for its support. It is not only by the 
means of a most curious structure of the bones 
that a man turns his head, but by virtue of an 
adjusted muscular power that he even holds it up. 

As another example of what we are illustrating, 
viz., conformity of use between the bones and the 
muscles, it has been observed of the different ver- 
tebrae, that their processes are exactly propor- 
tioned to the quantity of motion which the other 
bones allow of, and which the respective muscles 
are capable of producing. 

II. A muscle acts only by contraction. Its 
force is exerted in no other way. When the ex- 



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157 

NATURAL THEOLOGY- 

ertion ceases, it relaxes itself, that is, it ^^*;^^^^ 
by relaxation to its former state, but wxthout 
energy". This is the nature of the rrx^scular 

" Excellently ^ell as this is put. there is -o-^^'^^S 
moxe admixah/e still in the condition o^^^ ^^^^^^ 
system. With xespect to the support o^ f^^::tZ 
mentioned in the preceding page, ^"^^'^ ^^ ^^11 as 

braces, of course, the erect P-^- f ^^^^ eiaordinary 
the eqnable poising of the ^-^' ^;^»°;„, sensible of 
part of the phenomenon is this, thai ^c ^pm>,«^ 

the slightest inclination of the body or of any ^^^ '. 
although it would be difficult to say *° "^^^JJ";;'^^ 
acknowledged sensations this belongs. IMo ° ^ « 

feel every degree of inclination from the P^^^f^^'^Jj* 
in tte poising of the body, but ^e act upon ^'^^^^^ 
most minute correspondence of the muscles, l^e mu«. 

• -1 -K.,!- there IS a tine cob™^ 
cles are antagonists certainly, but tnere i 

biuation and adjustment in their acUon, ^^^^^^^ot 
illustrated by the two sawyers d-id^^g a 1^ of ^Oo^. 
The muscle having finished what we «^\^^;;^^^ or 
comxaction,is not in the condition of a loose rope Wo^ 

the contrary there is always - P«f««=\^^'?^;i^^V^^ 
preBervedbetweentheextentofrelaxationoftheonecUH« 

of ir^uscles. and the contraction of the other -^ tV.^re 
is ^ tone in both by which the limb may be sus^vx^ed 
ix. ax.y posture that is willed. This -^f;^^^^^^ted 
ix. tlxe Pbilosophical Transactions, f /^^ "^.^^^ -^ea- 

tise on the Hand, under the head of tbe M..«exxW 

Sense." 



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158 NATURAL THEOLOGY. 

fibre ; and being so^ it is evident that Uie recipro- 
cal energetic motion of the limbs> by which we 
mean motion voith force in opposite directions^ can 
only be product by the instrumentality of oppo- 
site or antagonist muscles — of flexors and exten- 
sors answering to each other. For instance^ the 
biceps and brachialis intemus muscles placed in 
the front part of the upper arm, by their contrac- 
tion, bend the elbow, and with such degree of 
force as the case requires or the strength admits 
of. The relaxation of these muscles after the effort 
would merely let the fore-arm drop down. For 
the back stroke, therefore, and that the arm may 
not only bend at the elbow, but also extend and 
straighten itself with force, other muscles, the 
longus and brevis brachialis externum, and the 
anconseus, placed on the hinder part of the arms, 
by theur contractile twitch, fetch back the fore- 
arm into a straight line with the cubit, with no 
less force than that with which it was bent out of 
it. The same thing obtains in all the limbs, and 
in every movable part of the body. A finger is 
not bent and straightened without the contraction 
of two muscles taking place. It is evident, there- 
fore, that the animal frinctions require that parti- 
cular disposition of the muscles which we describe 
by the name of antagonist muscles. And they 
are accordingly so disposed. Every muscle is 



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NATUKAL THEOLOGY. 159 

provided with an adversary. They act like two 
sawyers in a pit, by an opposite pull ; and no- 
thing, surely, can more strongly indicate de- 
sign and attention to an end than their being 
thus stationed, than this collocation. The na- 
ture of the muscular fibre being what it is, the 
purposes of the animal could be answered by 
no other. And not only the capacity for mo- 
tion, but the aspect and symmetry of the body 
is preserved by the muscles being marshalled 
according to this order — e.g., the mouth is holden 
in the middle of the £ice, ^nd its angles kept in 
a state of exact correspondency, by two muscles 
drawing against and balancing each other. In 
a hemiplegia, when the muscle on one side is 
weakened, the muscle on the other side draws the 
mouth awry. 

III. Another property of the muscles, .which 
could only be the result of care, is, their being 
almost universally so disposed as not to obstruct 
or interfere with one another's action. I know 
but one instance in which this impediment is per- 
ceived. We cannot easily swallow whilst we gape. 
This, I understand, is owing to the muscles em- 
ployed in the act of deglutition being so impli- 
cated with the muscles of the lower j aw, that whilst 
these last are contracted, the former cannot act 
with freedom. The obstruction is, in this instance. 



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160 NATURAL THEOLOGY. 

attended with Kttle inconvenience ; but it shows 
what the effect is where it does exist ; and what 
loss of faculty there would be if it were more fre- 
quent. Now, when we reflect upon the number 
of muscles, not fewer than four hundred and forty- 
six, in the human body, known and named*, how 
contiguous they lie to each other, in layers, as it 
were, over one another, crossing one another, 
sometimes embedded in one another, sometimes 
perforating one another — an arrangement which 
leaves to each its liberty, and its full play, must 
necessarily require me(}itation and counsel. 

IV. The following is oftentimes the case with 
the muscles. Their action is wanted where their 
situation would be inconvenient In which case 
the body of the muscle is placed in some commo- 
dious position at a distance, and made to commu- 
nicate with the point of action by slender strings 
or wires. If the muscles which move the fingers 
had been placed in the palm or back of the hand, 
they would have swelled that part to an awkward 
and clumsy thickness. The beauty, the propor- 
tions of the part, would have been destroyed. 
They are therefore disposed in the arm, and even 
up to the elbow, and act by long tendons strapped 
down at the wrist, and passing under the liga- 

• Keai'8 Anatomy, p. 295, ed. 3. 



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NATURAL THEOLOGY. 161 

ments to the fingers, and to the joints of the fin- 
gers which they are severally to move. In like 
manner^ the muscles which move the toes and 
many of the joints of the foot, how gracefiiUy are 
they disposed in the calf of the leg, instead of 
forming an unwieldy tumefaction in the foot 
itself! The observation may be repeated of the 
muscle which draws the nictitating membrane 
over the eye. Its office is in the front of the eye ; 
but its body is lodged in the back part of the 
globe, where it lies safe, and where it encumbers 
nothing* 

V. The great mechanical variety in the figure 
of the muscles may be thus stated. It appeara 
to be a fixed law that the contraction of a muscle 
shall be towards its centre. Therefore the sub- 
ject for mechanism on each occasion is, so to 
modify the figure and adjust the position of the 
muscle as to produce the motion required agree- 
ably with this law. This can only be done by 
giving to different muscles a diversity of configu- 
ration suited to their several offices, and to their 
situation with respect to the work which they 
have to perform. On which account we find them 
under a multiplicity of forms and attitudes ; some- 
times with double, sometimes with treble tendons, 
sometimes with none: sometimes one tendon to 
several muscles, at other times one m' ^cle to 



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162 NATURAL THEOLOGY. 

several tendons. The shape of the organ is sus- 
ceptible of an incalcnlable variety, whilst the ori- 
ginal property of the muscle, the law and line of 
its contraction, remains the same, and is simple. 
Herein the muscular system may be said to bear 
a perfect resemblance to our works of art. An 
artist does not alter the native quality of his 
materials, or their laws of action. He takes these 
as he finds them. His skill and ingenuity are 
employed in turning them, such as they are, to 
his account, by giving to the parts of his machine 
a form and relation in which these unalterable 
properties may operate to the production of the 
effects intended**. 

•* In the figure of a muscle, given in page 100, it 
may be observed that the tendons are on different sides 
of the muscle. 




B 

If we were to plan their arrangement it would be 
thus : A is the tendinous origin, and B the tendinous 
insertion; and the muscular fibres run obliquely be- 
tween them. This obliquity of the fibres is almost uni- 
versal in the muscles of the limb, and the effect is very 
important. It needs no reference to mechanics to under- 



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NATURAL THEOLOGY. 



163 



VI. The ejaculations can never too often be 
repeated— How many things must go right for us 

Btandj that if we pull ohliquely upon a weight we sacri- 
fice a great deal of power. For what advantage, then, 
is power resigned in the muscle ? " If you wish to draw 



€m 




a thing towards any place with the least force, you must 
pxdl directly in the line hetween the thing and the place ; 
hut if you wish to draw it as quickly as possible, and 
do not regard the loss of force, you must puU it ob- 
liquely, by drawing it in two directions at once. Tie 
a string to a stone A, and draw it straight towards you 
at C with one hand ; then make a loop on another string, 
and running the first through it, draw one string in each 
hand at B B, not towards you, in the line A C, but side- 
ways, till both strings are stretched in a straight line : 
you will see how much swifter the stone moves than it 
did before when pulled straightforward. Now this is 



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l64 NATURAL THEOLOGY. 

to be an hour at ease ! how many more for us to 
be vigorous and active ! Yet vigour and activity- 
are, in a vast plurality of instances, preserved in- 
human bodies, notwithstanding that they depend 
upon so great a number of instruments of motion, 
and notwithstanding that the defect or disorder 
sometimes of a very small instrument, of a single 
pair, for instance, out o^ the four hundred and 
forty-six muscles which are employed, may be 
attended with grievous inconveniency. There is 
piety and good sense in the following observa- 
tion taken out of the ' BeUgious Philosopher :' 
" With much compassion," says this writer, '^as well 
as astonishment at the goodness of our loving 
Creator, have I considered the sad state of a certain 
gentleman, who, as to the rest, was in pretty good 
health, but only wanted the use of these two little 

proved by mathematical reasoning to be the necessary 
consequence of forces applied obliquely ; there is a loss 
of power, but a great increase of velocity. The velocity 
is the thing required to be gained*." 

By the liberal employment of muscular power, quick- 
ness and variety of motion are obtained, and with the 
advantages which are so well described in the succeeding 
part of this chapter 

» Preliminary Treatise on the Objects, Advantages, and Plea- 
surea of Science. (Library of Useful Knowledge.) 



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NATURAL THEOLOGY. 165 

muscles that serve to lift up the eyelids, and so 
had almost lost the use of his sight, being forced, 
as long as this defect lasted, to shove up his eye- 
lids every moment with his own hands!" In 
general we may remark in how small a degree 
those who enjoy the perfect use of their organs 
know the comprehensiveness of the blessing, the 
variety of their obligation. They perceive a re- 
sult, but they think Uttle of the multitude of con- 
currences and rectitudes which go to form it. 

Besides these observations, which belong to the 
muscular organ as such, we may notice some ad- 
vantages of structure which are more conspicuous 
in muscles of a certain class or description than in 
others. Thus; 

I. The variety, quickness, and precision of 
which muscular motion is capable are seen, I 
think, in no part so remarkably as in the tongue. 
It is worth any man's while to watch the agility 
of his tongue, the wonderful promptitude with 
which it executes changes of position, and the 
perfect exactness. Each syllable of articulated 
sound requires for its utterance a specific action 
of the tongue, and of the parts adjacent to it. 
The disposition and configuration of the mouth 
appertaining to every letter and word, is not only 
peculiar, but, if nicely and accurately attended to, 
perceptible to the sight; insomuch, that curious 



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166 NATURAL THEOLOGY. 

persons have availed themselves of this circiim- 
stance to teach the deaf to speaks and to under- 
stand what is said by others. In the same person, 
and after his habit of speaking is formed, one, 
and only one, position of the parts will produce a 
given articulate sound correctly. How instanta- 
neously are these positions assumed and dis- 
missed ! how numerous are the permutations, how 
various, yet how infallible ! Arbitrary and antic 
variety is not the thing we admire ; but variety 
obeying a rule, conducing to an efTect, and com- 
mensurate with exigencies infinitely diversified. 
I believe also that the anatomy of the tongue 
corresponds with these observations upon its 
activity. The muscles of the tongue are so nu- 
merous, and so impUcated with one another, that 
they cannot be traced by the nicest dissection ; 
nevertheless (which is a great perfection of the 
organ) neither the number, nor the complexi^, 
nor what might seem to be the entanglement of 
its fibres, in anywise impede its motion, or ren- 
der the determination or success of its efforts 
imcertain. 



I here entreat the reader's permission to step 
a little out of my way, to consider the parts of the 
mofttth in some of their other properties. It has 



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NATURAL THEOLOGY. 167 

been said^ and that by an eminent physiologist, 
that, whenever nature attempts to work two or 
more purposes by one instrument, she does both 
or all imperfectly. Is this true of the tongue re- 
garded as an instrument of speech and of taste, 
or regarded as an instrument of speech, of taste, 
and of deglutition? So much otherwise, that 
many persons, that is to say, nine hundred and 
ninety-nine persons out of a thousand, by the 
instrumentahty of this one organ, talk, and taste, 
and swallow very well. In feet, the constant 
warmth and moisture of the tongue, the thinness 
of the skin, the papiUse upon its surface, quaHfy 
this organ for its office of tasting, as much as its 
inextricable multiplicity of fibres do for the rapid 
movements which are necessary to speech. Ani- 
mals which feed upon grass have their tongues 
covered with a perforated skin, so as to admit the 
dissolved food to the papillae underneath, which, 
in the meantime, remain defended from the rough 
action of the imbruised spiculse. 

There are brought together within the cavity 
of the mouth more distinct uses, and parts exe- 
cuting more distinct offices, than I think can be 
found lying so near to one another, or within the 
same compass, in any other portion of the body : 
viz., teeth of difiTerent shape, first for cutting, 
secondly for grinding; muscles, most artificially 



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168 NATURAL THEOLOGY^ 

disposed for carrying on the compound motion of 
the lower jaw, half lateral and half vertical, by 
which the mill is worked: fountains of saliva, 
springing up in different parts of the cavity for 
the moistening of the food, whilst the mastication 
is going on: glands, to feed the fountains; a 
muscular constriction of a very peculiar kind in 
the back part of the cavity, for the guiding of the 
prepared aliment into its passage towards the 
stomach, and in many cases for carrying it along 
that passage ; for, although we may imagine this 
to be done simply by the weight of the food 
itself, it in truth is not so, even in the upright 
posture of the human neck ; and most evidently 
is not the case with quadrupeds — ^with a horse, 
for instance, in which, when pasturing, the food is 
thrust upward by muscular strength instead of 
descending of its own accord. 

In the mean time, and within the same cavity, 
is going on another business, altogether different 
from what is here described — ^that of respiration 
and speech. In addition, therefore, to all that 
has been mentioned, we have a passage opened 
from this cavity to the lungs, for the admission of 
air exclusively of every other substance : we have 
muscles, some in the larynx, and without number 
in the tongue, for the purpose of modulating that 
air in its passage, with a variety, a compass, and 



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NATURAL THEOLOGr. 169 

precision, of which no other musical instrument is 
capable. And lastly, which, in my opinion, crowns 
the whole as a piece of machinery, we have a spe- 
cific contrivance for dividing the pneumatic part 
from the mechanical, and for preventing one set 
of actions interfering with the other. Where 
various functions are united, the diflBculty is to 
guard against the inconveniences of a too great 
complexity. In no apparatus put together by 
art and for the purposes of art, do I know such 
multifarious uses so aptly combined, as in the 
natural organization of the human mouth ; or 
where the structure, compared with the uses, is 
so simple. The mouth, with all these intentions 
to serve, is a single cavity ; is one machine ; with 
its parts neither crowded nor confused, and each 
unembarrassed by the rest: each at least at 
liberty in a degree sufficient for the end to be 
attained. If we cannot eat and sing at the same 
moment, we can eat one moment and sing the 
next: the respiration proceeding freely all the 
while. 

There is one case, however, of this double 
office, and that of the earliest necessity, which the 
mouth alone could not perform ; and that is, car- 
rying on together the two actions of sucking and 
breathing. Another route therefore is opened 
for the air — namely, through the nose— rwhich 

I 



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170 NATURAL THEOLOGY. 

lets the breath pass backward and forward, whilst 
the lips, in the act of sucking, are necessarily shut 
close upon the body from which the nutriment is 
drawn. This is a circumstance which always ap- 
peared to me worthy of notice. The nose would 
have been, necessary, although it had not been 
the organ of smelling. The making it the seat 
of a sense was superadding a new use to a part 
already wanted ; was taking a wise advantage of 
an antecedent and a constitutional necessity .*• 

•• When our author describes the variety of functions 
performed by the mouth and tongue, he is in admiration 
at the simplicity of the instrument. But this is only an 
apparent simplicity : the complexity of structure is con- 
cealed. Indeed, it has been this very consideration 
which led to the new investigations into the nervous 
system. Without entering far into this subject, we take 
the tongue in illustration. It is a fine organ of touch : 
it is the seat of the sense of taste : it is necessary to 
deglutition : its modulations are infinite in speech ; but 
the reason of a body so simple in its outward form being 
capable of performing offices apparently so discordant, 
is visible only to the 'anatomist, who traces the nerves 
into this organ. Then he discovers, besides the nerve 
proceeding from the papillae of the tongue to the senso- 
rium, that there are nerves of voHtion governing the 
muscles t)f the tongue. In addition to these, there is a 
nerve which regulates the action of swallowing, and 



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NATURAL THEOLOGY. 171 

But to return to that which is the proper sub- 
ject of the present section — the celerity and pre- 
dsion of muscular motion. These qualities may 
be particularly observed in the execution of many 
species of instrumental music, in which the changes 
produced by the hand of the musician are exceed- 
ingly rapid; are exactly measured, even when 
most minute; and display, on the part of the 
muscles, an obedience of action alike wonderftd 
for its quickness and its correctness. 

Or let a person only observe his own hand 
whilst he is writing; the number of muscles 
which are brought to bear upon the pen; how 
the joint and adjusted operation of several ten- 

which combines the motions of the gullet with, those of 
the tongue; and in the same manner another nerve, 
tending to the organ of voice in the larynx, branches off 
to the tongue, and associates it with the organ of th^ 
voice, so as to produce articulate language : these nervous 
cords are the true organization by which one member, 
simple in its exterior form, has a complexity in its in- 
ternal relations. And thus it is, that in many instances 
organs which are apparently simple, and through which 
we perform many offices so easily that we think not at 
all of what is necessary to their execution, have yet in- 
ternally, and to the eye of the anatomist, a thousand 
minute circumstances or relations on which the perfec- 
tion of their action depends. 

I 2 



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172 NATURAL THEOLOGY. 

dons is concerned in every stroke, yet that five 
hundred such strokes are drawn in a minute. 
Not a letter can be turned without more than 
one, or two, or three tendinous contractions, defi- 
nite, both as to the choice of the tendon, and as 
to the space through which the contraction moves ; 
yet how currently does the work proceed ! and 
when we look at it, how faithful have the muscles 
been to their duty — ^how true to the order which 
endeavour or habit hath inculcated ! For let it 
be remembered, that, whilst a man's hand-writing 
is the same, an exactitude of order is preserved, 
whether he write well or ill. These two instances 
of music and writing show not only the quick- 
ness and precision of muscular action, but the 
docility. 

II. Regarding the particular configuration of 
muscles, sphincter or circidar muscles appear to 
be admirable pieces of mechanism. It is the 
muscular power most happily applied ; the same 
quality of the muscular substance, but under a 
new modification. The circular disposition of 
the fibres is strictly mechanical ; but, though the 
most mechanical, is not the only thing in sphinc- 
ters which deserves our notice. The regulated 
degree of contractile force with which they are 
endowed, sufficient for retention, yet vincible when 
requisite, together with their ordinary state of 



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I 



NATURAL THEOLOGY. 173 

actual contraction, by means of which their de- 
pendence upon the will is not constant but occa- 
sional, gives to them a constitution of which the 
conveniency is inestimable. This their semi- 
voluntary character is exactly such as suits with 
the wants and functions of the animal. 

III. We may also, upon the subject of muscles, 
observe, that many of our most important actions 
are achieved by the combined help of different 
muscles. Frequently, a diagonal motion is pro- 
duced by the contraction of tendons pulling in 
the direction of the sides of the parallelogram. 
This is the case, as hath been already noticed, 
with some of the oblique nutations of the head. 
Sometimes the number of co-operating muscles is 
very great. Dr. Nieuentyt, in the Leipsic Trans- 
actions, reckons up a hundred muscles that are 
employed every time we breathe ; yet we take in, 
or let out, our breath, without reflecting what a 
work is thereby performed ; what an apparatus is 
laid in of instruments for the service, and how 
many such contribute their assistance to the 
effect. Breathing with ease is a blessing of every 
moment; yet of all others it is that which we 
possess with the least consciousness. A man in 
an asthma is the only man who knows how to 
estimate it. 



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174 NATURAL THEOLOGY. 

IV. Mr. Home has observed,* that the most 
important and the most delicate actions are per- 
formed in the body by the smallest muscles ; and 
he mentions, as his examples, the muscles which 
have been discovered in the iris of the eye, and 
the drum of the ear. The tenuity of these mus- 
cles is astonishing : they are microscopic hairs ; 
must be magnified to be visible; yet are they 
real effective muscles: and not only such, but 
the grandest and most precious of our faculties, 
sight and hearing, depend upon their health and 
action. 




[The figure here represents the action of the biceps 
muscle which lies on the arm, and is inserted upon the 
radius of the fore-arm in sustaining a weight in the 
hand.] 

V, The muscles act in the limbs with what is 
called a mechanical disadvantage. The muscle 
at the shoulder, by which the arm is raised, is 
fixed nearly in the same manner as the load is 

* Phil. Trans, part i. 1800, p. 8. 



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NATURAL THEOLOGY. 175 

fixed upon a steelyard, within a few decimals, we 
will say, of an inch from the centre upon which 
the steelyard turns. In this situation, we find 
that a very heavy draught is no more than sufE- 
tsient to countervail the force of a small lead 
plummet, placed upon the long arm of the steel- 
yard, at the distance of perhaps fifteen or twenty 
inches from the centre and on the other side of 
it. . And this is the disadvantage which is meant; 
and an absolute disadvantage, no doubt, it would 
be, if the object were to spare the force of mus- 
cular contraction. But observe how conducive is 
this constitution to animal conveniency. Mecha- 
nism has always in view one or other of these two 
purposes — either to move a great weight slowly, 
and through a small space, or to move a light 
weight rapidly, through a considerable sweep. 
JFor the former of these purposes, a different spe- 
cies of lever, and a different collocation of the 
muscles, might be better than the present; but 
for the second, the present structure is the true 
one. Now so it happens, that the second, and 
not the first, is that which the occasions of animal 
life principally call for. In what concerns the 
human body, it is of much more consequence to 
any man to be able to carry his hand to his head 
with due expedition, than it would be to have the 
power of raising from the ground a heavier load 



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176 NATURAL THEOLOGY. 

(of two or three more hundred weight, we will 
suppose) than he can lift at present. 

This last is a faculty, which, on some extraor- 
dinary occasions, he may desire to possess; but 
the other is what he wants and uses every hour 
or minute. In like manner, a husbandman or a 
gardener will do more execution, by being able to 
carry his scythe, his rake, or his flail, with a suffi- 
cient despatch through a sufficient space, than if, 
with greater strength, his motions were propor- 
tionably more confined and slow. It is the same 
with a mechanic in the use of his tools. It is the 
same also with other animals in the use of their 
limbs. In general, the vivacity of their motions 
would be ill exchanged for greater force under a 
clumsier structure. 

We have offered our observations upon the 
structure of muscles in general; we have also 
noticed certain species of muscles ; but there are 
also single muscles which bear marks of mecha- 
nical contrivance appropriate as well as parti- 
cular. Out of many instances of this kind we 
select the following : — 

I. Of muscular actions, even of those which 
are well understood, some of the most curious 
are incapable of popular explanation; at least, 
without the aid of plates and figures. This is in 
a great measure the case with a very familiar. 



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NATURAL THEOLOGY. 177 

but, at the same time, a very complicated motion, 
that of the lower jaw ; and with the muscular 
structure by which it is produced. One of the 
muscles concerned may, however, be described in 
such a manner as to be, I think, sufficiently com- 
prehended for our present purpose. The pro- 
blem is to pull the lower jaw doii?n. The obvious 
method shoidd seem to be, to place a straight 
muscle — viz., to fix a string from the chin to the 
breast, the contraction of which would open the 
mouth, and produce the motion required at once. 
But it is evident that the form and liberty of the 
neck forbid a muscle being laid in such a posi- 
tion ; and that, consistently with the preservation 
of this form, the motion which we want must be 
eflFectuated by some muscular mechanism dis- 
posed farther back in the jaw. The mechanism 
adopted is as follows : — A certain muscle, called 
the digastric, rises on the side of the face, consi- 
derably above the insertion of the lower jaw, and 
comes down, being converted in its progress into 
a round tendon. Now it is manifest that the 
tendon, whilst it pursues a direction descending 
towards the jaw, must, by its contraction, pull the 
jaw up instead of down. What then was to be 
done ? This, we find, is done : The descending 
tendon, when it is got low enough, is passed 
through a loop, or ring, or pulley, in the os 

i3 



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178 NATURAL THEOLOGY. 

hyoides; and then made to ascend; and having 
thus changed its line of direction, is inserted into 
the inner part of the chin : by which device, viz^ 
the turn at the loop, the action of the mnsde 
(which in all muscles is contractidn) that before 
would have pulled the jaw up, now as necessarily 
draws it down. " The mouth," says Heister, "is 
opened by means of this trochlea in a most won^ 
derful and elegant manner." 

II. What contrivance can be more mechanical 
than the foUowing, viz., a slit in one tendon to let 
another tendon pass through it ? This structure 
is found in the tendons which move the toes and 
fingers. The long tendon, as it is called, in the 
foot, which bends the first joini of the toe, passes 
through the shcnrt tendon which bends the second 
joint, which course allows to the sinew more 
liberty, and a more commodious action than it 
would otherwise have been capable of exerting.* 
There is nothing, I believe, in a silk or cotton 
mill, in the belts, or straps, or ropes, by which 
motion is communicated from one part of the ma- 
chine to another, that is more artificial, or more 
evidently so, than this j>er/bra^ioR. - 

IIL The next circumstance which I shall men- 
tion under this head of muscular arrangement is 

• Chet. Anat. p. 119. 



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NATURAL THEOLOGY. 179 

sa decisive a mark of intention^ that it always ap- 
peared to me to supersede^ in some measure, the 
necessity of seeking for any other observation 
upon the subject ; and that circumstance is, the 
tendons which pass from the leg to the foot, being 
bound ^wn by a ligament to the ankle. The 
foot is placed at a considerable angle with the leg. 
It is manifest, therefore, that flexible strings, 
passing along the interior of the angle, if left to 
themselves, would, when stretched, start from it. 
The obvious preventive is to tie them down. And 
this is done in fact. Across the instep, or rather 
just above it, the anatomist finds a strong liga- 
ment, under which the tendons pass to the foot. 
The effect of the ligament as a bandage can be 
made evident to the senses ; for if it be cut, the 
tendons start up. The simplicity, yet the clear- 
ness of this contrivance, its exact resemblance to 
established resources of art, place it amongst the 
most indubitable manifestations of design with 
which we are acquainted. 

There is also a further use to be made of the 
present example, and that is, as it precisely ^on- 
tracticts the opinion that the parts of animals may 
have been all formed by what is called appetency, 
t. e., endeavour perpetuated and imperceptibly 
working its effect through an incalculable series of 
generations. We have here no endeavour, but 



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180 NATURAL THEOLOGY. 

the reverse of it — a constant renitency and reluc- 
tance. The endeavour is all the other way. The 
pressure of the Ugament constrains the tendons ; 
the tendons re-act upon the pressure of the liga- 
ment. It is impossible that the Ugament shoidd 
ever have been generated by the exercise of the 
tendon, or in the course of that exercise, foras- 
much as the force of the tendon perpendicularly 
resists the fibre which confines it, and is con- 
stantly endeavouring, not to form, but to rupture 
and dis{dace, the threads of which the ligament is 
composed. 



Keill has reckoned up in the human body four 
hundred and forty-six muscles, dissectible and 
describable; and hath assigned a use to every 
one of the number. This cannot be all imagi- 
nation. 

Bishop Wilkins hath observed from Galen, that 
there are at least ten several qualifications to be 
attended to in each particular muscle — ^viz., its 
proper figure; its just magnitude; its fulcrum; 
its point of action, supposing the figure to be 
fixed ; its collocation with respect to its two ends, 
the upper and the lower ; the place ; the position 
of the whole muscle ; the introduction into it of 
nerves, arteries, veins. How are things including 



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NATURAL THEOLOGY. 181 

80 many adjustments to be made ; or, when made, 
how are they to be put together, without intel- 
ligence ? 

. I have sometimes wondered why we are not 
struck with mechanism in animal bodies as readily 
and as strongly as we are struck with it, at first 
sight, in a watch or a mill. One reason of the 
difference may be, that animal bodies are, in a 
great measure, made up of soft flabby substances, 
such as muscles and membranes; whereas we 
have been accustomed to trace mechanism in 
sharp lines, in the configuration of hard mate- 
rials, in the moulding, chiseling, and filing into 
shapes of such articles as metals or wood. There 
is something therefore of habit in the case ; but 
it is sufficiently evident that there can be no 
proper reason for any distinction of the sort. 
Mechanism may be displayed in the one kind of 
substance as well as in the other. 

Although the feAV instances we have selected, 
even as they stand in our description, are nothing 
short, perhaps, of logical proofs of design, yet 
it must not be forgotten, that, in every part of 
anatomy, description is a poor substitute for in- 
spection. It is well said by an able anatomist*, 
and said in reference to the very part of the sub- 

* Steno, io Bias. Anat. Animal, p. 2, c, 4. 



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182 MATCTRAL THEOLOGY. 

ject which we have been treating of: — ''Imper- 
fecta haec musculorum descriptio non min^ 
arida est legentibus qudm inspectantibus ftierit 
jucunda eorundem prseparatio. Elegantissima 
enim mechanic's artificia, creberrim^ m illis obria^ 
verbis nonnisi obscur^ exprimuntur: camium au^ 
tem ductu, tendinum colore, insertionum propor- 
tioned et trochlearium distributione, oculis expo^ 
fflta, omnem superant admirationem.** 



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KATUKAL THEOLOGY. 



183 



CHAPTER X. 

OF THE VESSELS OF ANIMAL BODIES. 




[The figure represents the heart and great blood-ves- 
sels, and may convey some idea of the circulation of the 
blood. We understand A to be the great vein returning 
the blood from the body ; B the right sinus or auricle. 



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184 NATURAL THBOLOOT. 

From this cavity of the heart, the blood is carried into 
C, the ventricle ; and from this ventricle the pulmonary 
artery goes off. This great artery of the lungs is for the 
conveyance of the blood which is returned from the body 
into the lungs. Now the great vein A, the auricle B, 
the ventricle C, and the pulmonary artery D D, belong 
to the right side of the heart; or, to take a more impor- 
tant distinction, they convey dark-coloured blood, which 
is unfit for the uses of the system. But when this blood 
reaches the lungs, and is exposed to the atmosphere we 
breathe, it throws off the carbon, becomes bright in 
colour, and is called arterial blood. It returns to the 
heart, not to the cavities which we have enumerated, but 
by the veins of the lungs to the other side of the heart, 
the left — ^that is, to another auricle and another ven- 
tricle. From this left ventricle there ascends the aorta, 
the great artery of the body, E E. This great vessel 
conveys the blood to every part that has life. From all 
the parts of the body the blood is gathered again by the 
extremities of the veins, and so returns to the point of 
the auricle from which we began to trace it. This short 
preface may make the observations of the author easily 
intelligible.] 



The circulation of the blood through the bodies of 
men and quadrupeds^ and the apparatus by which 
it is carried on^ compose a system^ and testify a 
contrivance, perhaps the best understood of any 
part of the animal frame. The lymphatic system. 



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NATURAL THEOLOGY, 185 

or the nervous system^ may be more subtle and 
intricate — nay, it is possible that in their structure 
they may be even more artificial than the sangui- 
ferous — ^but we do not know so much about them. 

The utility of the circulation of the blood I 
assume as an acknowledged point. One grand 
purpose is plainly answered by it — the distributing 
to every part, every extremity, every nook and 
comer of the body, the nourishment which is re- 
ceived into it by one aperture. What enters at 
the mouth finds its way to the fingers' ends. A 
more difficult mechanical problem could hardly, I 
think, be proposed, than to discover a method of 
constantly repairing the waste, and of supplying 
an accession of substance to every part of a com- 
plicated machine at the same time^. 

This system presents itself under two views : 
first, the disposition of the blood-vessels, i. e,, the 
laying of the pipes ; and, secondly, the construc- 
tion of the engine at the centre, viz., the heart, for 
driving the blood through them. 

I. The disposition of the blood-vessels, as far 
as regards the supply of the body, is like that of 
the water-pipes in a city, viz., large and main 
trunks branching off by smaller pipes (and these 

•'^ We must refer our reader to the dissertation in the 
Appendix, on the circulation of the blood and its uses. 



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186 NATURAL THECHLOOY. 

again bj still narrower tubes) in every directi(»E^ 
and towards every part in which the fluid which 
they convey can be wanted. So far the water- 
jpipes which serve a town may represent the ves- 
sels which carry the blood from the heart. But 
there is another thing necessary to the bloody 
which is not wanted for the water ; and that is, 
the carrying of it back again to its source. For 
ihis oflSce, a reversed system of vessels is prepared, 
which, uniting at their extremities with the ex- 
tremities of the first system, collects the divided 
and subdivided streamlets, first, by capillary rami- 
fications into larger branches, secondly, by these 
branches into trunks ; and thus returns the blood 
(almost exactly inverting the order in which it 
went out) to the fountain whence its motion pro- 
<;eeded. All which is evident paechanism. 

The body, therefore, contains two systems of 
J)lood-v^ssels, arteries and veins. Between the 
constitution of the systems there are also two dif- 
ferences, suited to the frmctions which the systems 
have to execute. The blood, in going out, pass- 
ing always from wider into narrower tubes ; and, 
in coming back, from narrower into wider, it is 
evident that the impulse and pressure upon the 
sides of the blood-vessel will be much greater in 
one case than the other. Accordingly, the arte- 
ries which carry out the blood are formed of much 



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NATURAL THEOLOGY. 187 

tougher and stronger coats than the veins which 
bring it back. That is one difference : the othe^ 
is still more. artificial^ or, if I may so speak, indi- 
cates still more clearly the care and anxiety of the 
artificer. Forasmuch as, in the arteries, by rea* 
son of the greater force with which the blood is 
urged along them, a wound or rupture would be 
more dangerous than in the veins, these vessels 
are defended firom injury, not only by their tex- 
ture, but by their situation, and by every advantage 
of situation which can be given to them. They 
are buried in sinuses, pr they creep along grooves 
made for them in the bones ; for instance, the 
under edge of the ribs is sloped and furrowed 
^lely for the passage of these vessels. Sometimes 
they proceed in channels, protected by stout para- 
pets on each side, which last description is re- 
markable in the bones of the fingers, these being 
hollowed out, on the under-side, like a scoop, and 
with such a concavity> that the finger may be cut 
across to the bone, without hurting the artery 
which runs along it. At other times, the arteries 
pass in canals wrought in the substance, and in 
the very middle of the substance, of the bone. 
This takes place in the lower jaw; and is found 
where there would, otherwise, be danger of com* 
pression by sudden curvature. All this care is 
wonderful, yet not more than what the importance 



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188 NATURAL THEOLOGY. 

of the case required. To those who venture their 
lives in a ship^ it has been often said^ that there 
is only an inch-board between them and death ; 
but in the body itself, especially in the arterial 
system, there is, in many parts, only a membrane^ 
a skin, a thread. For which reason, this system 
lies deep under the integuments; whereas the 
veins, in which the mischief that ensues from in- 
juring the coats is much less, lie in general above 
the arteries; come nearer to the surface; are 
more exposed. 

It may be further observed concerning the two 
systems taken together, that though the arterial, 
with its trunk and branches and small twigs, may 
be imagined to issue or proceed — ^in other words, 
to grow from the heart, like a plant from its 
root, or the fibres of a leaf from its foot-stalk 
(which however, were it so, would be only to 
resolve one mechanism into another); yet the 
venal, the returning system, can never be formed 
in this manner. The arteries might go on shoot- 
ing out from their extremities — i. e., lengthening 
and subdividing indefinitely; but an inverted 
system, continually uniting its streams, instead 
of dividing, and thus carrying back what the 
other system carried out, could not be referred to 
the same process. 

II. The next thing to be considered is the 



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NATURAL THEOLOGY. 189 

engine which works this machinery — viz., the 
heart* For our purpose it is unnecessary to 
ascertain the principle upon which the heart acts: 
Whether it be irritation excited by the contact^ of 
the blood, by the influx of the nervous fluid, or 
whatever else be the cause of its motion, it is 
something which is capable of producing, in a 
living muscular fibre, reciprocal contraction and 
relaxation. This is the power we have to work 
with ; and the inquiry is, how this power is ap- 
phed in the instance before us. Thiere is pro- 
vided, in the central part of the body, a hollow 
muscle, invested with spiral fibres, running in 
both directions, the layers intersecting one an- 
other ; in some animals, however, appearing to be 
semicircular rather than spiral. By the contrac- 
tion of these fibres, the sides of the muscular 
cavities are necessarily squeezed together, so as 
to force out from them any fluid which they may 
at that time contain : by the relaxation of the 
same fibres, the cavities are in their turn dilated, 
and, of course, prepared to admit every fluid 
which may be poured into them. Into these 
cavities are inserted the great trunks, both of the 
arteries which carry out the blood, and of the 
veins which bring it back. This is a general 
account of the apparatus ; and the simplest idea 
of its action is, that by each contraction a portion 
of blood is forced by a syringe into the arteries ; 



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190 NATURAL THEOLOGY. 

and> at each dilatation^ an equal portion is re- 
ceived from the veins. This produces, at each 
pulse, a motion, and change in the mass of blood, 
to the amount of what the cavity contains, which 
in a ftill-grown human heart I understand is about 
an ounce, or two table-spoons fiill. How quickly 
these changes succeed one another, and by this 
succession how sufficient they are to support a 
stream or circulation throughout the system, may 
be understood by the following computation, 
abridged from Keill's Anatomy, p. 117, ed. 3.: 
^^Each ventricle will at least contain one ounce of 
blood. The heart contracts four thousand times 
in one hour: from which it follows, that there 
pass through the heart, every hour, four thousand 
ounces, or three hundred and fifty pounds of 
blood. Now the whole mass of blood is said to 
be about twenty-five pounds : so that a quantity 
of blood, equal to the whole mass of blood, passes 
through the heart fourteen times in one hour, 
which is about once in every four minutes." 

Consider what an affisiir this is, when we come 
to very large animals. The aorta of a whale is 
larger in the bore than the main pipe of the 
water- works at London Bridge; and the water 
roaring in its passage through that pipe is in- 
ferior, in impetus and velocity, to the blood gush- 
ing from the whale's heart. Hear Dr. Hunter's 
account of the dissection of a whale : '' The aorta 



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NATURAL THE<MX)GY. 191 

measured a foot diameter. Ten or fifteen gallons 
of blood are thrown oiit of the heart at a stroke 
with an immense velocity, through a tube of a 
foot diameter. The whole idea fills the mind 
with wonder."* 

The account which we have here stated, of the 
injection of blood into the arteries by the contrac- 
tion, and of the corresponding reception of it 
from the veins by the dilatation, of the cavities of 
the heart, and of the circulation being thereby 
maintained through the blood-vessels of the body, 
is true, but imperfect. The heart performs this 
office, but it is in conjunction with another of 
equal curiosity and importance. It was necessary 
that the blood should be successively brought 
into contact, or contiguity, or proximity with the 
air. I do not know that the chemical reason, 
upon which this necessity is founded, has been 
yet sufficiently explored. It seems to be made 
appear, that the atmosphere which we breathe is 
a mixture of two kinds of air : one pure and vital, 
the other, for the purposes of Hfe, efifete, foul, and 
noxious ;* that when we have drawn in our breath 



■* The atmosphere contains, in every 100 parts, of 
oxygen 21 parts; nitrogen or azote, 19 parts ; carbonic 
acid gas, a fractional part. 

* Dr. Hunter's Account of the DissecUon of a Wbale.-(PhU. 
Trans.) 



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192 NATURAL THEOLOGY. 

the blood in the lungs imbibes from the air thus 
l»:ought into contiguity witli it a portion of its 
pure ingredient^ and at the same time gives out 
the efifete or corrupt air which it contained, and 
which is carried away, along with the halitus, 
every time we expire. At least, by comparing 
the air which is breathed from the lungs with the 
air which enters the lungs, it is found to have lost 
some of its pure part, and to have brought away 
with it an addition of its impure part. Whether 
these experiments satisfy the question as to the 
need which the blood stands in of being visited 
by continual accesses of air, is not for us to in- 
quire into, nor material to our argument: it is 
sufficient to know, that, in the constitution of 
most animals, such a necessity exists, and that 
the air, by some means or other, must be intro- 
duced into a near communication with the blood.** 

*• The most simple view, and the best supported, is 
this — that the dark venous blood which is returning 
from the circulation through the body is loaded with 
carbon. When it is carried to the right side of the 
heart, and from that into the lungs, the branches of the 
pulmonary artery are distributed in great minuteness on 
cells infinite in number. These cells communicate with 
the extreme branches of the windpipe ; and as the at- 
mosphere is received into these cells, the circulating 
blood comes to be exposed to its influence ; for neither 



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NATURAL THEOLOGY. 193 

The lungs of animals are constructed for this 
purpose. They consist of blood-vessels and air- 
vessels, lying close to each other ; and whenever 
there is a branch of the trachea or windpipe, 
there is a branch accompanying it of the vein and 
artery, and the air-vessel is always in the middle 
between the blood-vessels.* The internal sur- 
face of these vessels, upon which the application 
of the air to the blood depends, would, if col- 
lected and expanded, be, in a man, equal to a 
superficies of fifteen feet square. Now, in order 
to give the blood in its course the benefit of this 
organization (and this is the part of the subject 
with which we are chiefly concerned), the follow- 
ing operation takes place. As soon as the blood 
is received by the heart from the veins of the 
body, and before that is sent out again into its 
arteries, it is carried, by the force of the contrac- 

the coats of the minute vessels which contain the blood, 
nor the fine membrane of the cells which contain the 
air, prevents the influence of the atmosphere upon the 
blood. The carbon of the blood meeting the oxygen in 
the atmosphere, forms carbonic acid gas ; and the air 
expelled in expiration, thus loaded, carries away, of 
courae, a portion of moisture by exhalation. (See the 
dissertation entitled — On the Circulation. Appendix.) 

• KeiU'i Anatomy, p. 121. 



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1114 



NATURuVL THEOLOGY. 




[ The figure represents the two sides of the heart se- 
parated : that to the left of the figure, but on the right 
side of the body, containing the venous blood whii^ 
must pass through the lungs to serve the purposes of 
the economy ; and that on the left side, containing arte- 
rial blood, which is sent out into the body. Man, and 
all animals of warm blood, have the whole mass of blood 
passing through the lungs, and a double heart, as here 
represented, each consisting of a vein, an auricle, a vea- 
tricle, and an artery. The arrows point out the course 
of the circulation.] 



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NATURAL THEOLOGY. 195 

«>n of the heart, and by means of a separate and 
««Pplementary artery, to the lungs, and made to 

iTJr *^ ^^^^ **^ *® \\mgB; from which, after 
> has undergone the action, whatever it be, of 
flat viscus, it is brought back by a large vein 
once more to the heart, in ordw, when thus con- 
cocted and prepared, to be thence distributed 
anew into the system. This assigns to the heart 
e office. The pulmonary circulation is a 
sys em within a system ; and one action of the 
Fol^ **».« origin of both. 

tJiis complicated fonction four caidties 

. , ^^cessary, and four are accordingly pro- 

hi ri ^^ called ventricles, which send out the 

s ance; the oth^ i^to the mass, after it has 
^ uroed from the lungs; two others also, called 
a^ncles, whteh receitw the blood from the vems, 
-^ <me^ as it comes immediately from the body ; 
^ er, as the same blood comes a second time 
th ^^ ^^ ^^«^^ation through the lungs. So that 
^ are two receiving cavities, and two forcing 
iT structure of the heart has reference 

o the lung^ . f^y wUhout the lungs, one of each 
TOald ha.^e l>ee3i sufficient. The translation <^ 
tiae blood ixi the heart itself is after this manner. 
-^he reoeiTrmg eavities respectively commniiicate 

k2 



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196 NATURAL THEOLOGY. 

with the forcing cavities, and, by their contrac- 
tion, unload the received blood into them. The 
forcing cavities, when it is their turn to contract, 
compel the same blood into the mouths of the 
arteries. 

The account here given will not convey to a 
reader ignorant of anatomy any thing like an 
accurate notion of the form, action, or use of the 
parts (nor can any short and popular account do 
this) ; but it is abundantly sufficient to testify 
contrivance ; and although imperfect, being true 
as far as it goes, may be relied upon for the only 
purpose for which we oflTer it — the purpose of this 
conclusion. 

"The wisdom of the Creator," saith Ham- 
burgher, "is in nothing seen more gloriously 
than in the heart." And how well doth it exe- 
cute its office ! An anatomist, who understood 
the structure of the heart, might say beforehand 
that it woidd play ; but he woidd expect, I think, 
from the complexity of its mechanism, and the 
delicacy of many of its parts, that it should always 
be liable to derangement, or that it would soon 
work itself out. Yet shall this wdnderM machine 
go, night and day, for eighty years together, at 
the rate of a hundred thousand strokes every 
twenty-four hours, having, at every stroke, a great 



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NATURAL THEOLOGY. 197 

resistance to overcome; and shall continue this 
action for this length of time, without disorder 
and without weariness ! 




[This figure will assist the explanation of the following 
pages. It presents a section of the ventricle and the 
artery. Suppose that the blood enters in the direction 
of the arrow, it passes between two valves, of very parti- 
cular construction. They are of a triangular shape, and 
held out by little cords, which are called the cor dee 
tendinece. These cords are attached to muscles, which, 
from their appearance, are called columnce carnece ; and 
these fibres are continuous with the fibrous substance 
of the heart itself. Now when the ventricle is distended 
with blood, the valves are drawn by their tendons in such 
a manner as almost to close the orifice ; and certainly so 
to dispose them, that the instant the blood takes a direc- 



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198 NATURAL THEOLOGY. 

tkm btckward into the Tein by the eoatrtctm ot the 
TentriclCy they fall together, and like a fiood-gate stop 
the current in that direction. W^re there no eorda 
tendineae or colunvMB camece^ these valves would be 
floated back into the auricle, and lose their office. But 
the most admirable part of the contrivance is, that the 
columnce cam^^r receiving the same impulse to contract 
as the walls of the heart itself, act at the same instant 
with it ; and by contracting in proportion as the walls 
approach each other, they hold the margins of the valves 
hke the leeches of a sail when bagged by the wind. 
The blood being prevented passing backward is urged 
into the great artery still in the directioii of the arrow. 
And now it will be observed that the artery must be 
dilated when the heaart contracts. And the artery itself 
being Both elastic and muscular, reacting upon this im- 
pulse, it will contract while the ventricle b dilating. The 
blood would fall back from the great artery into the 
ventricle, were it not again prevented by the mechanical 
intervention of valves, a represents the semihrnar vahre 
of the aorta at the root of that great artery ; and it ia a 
surprising thing to see how offices so nearly alike are 
performed by a mechanism entirely different. This 
valve consists oi three little bags, which are driven up 
by the force of the blood in the natural course of the 
circulation ; but when, by the action of the aorta, the 
blood makes a motion backwards, it fills these three 
little bags, and they fiedl together, and prevent the blood 
flowing back into the heart.] 



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NATURAL THEOLOGY. 199 

But Airther : from the account which has been 
giyen of the medianism o£ the heart, it is evident 
that it must require the interposition of vaive9 ; 
that the success indeed of its action must depend 
upon these ; for when any one of its cavities con- 
tracts, the necessary tendency of the force will be 
to drive the enclosed blood, not only into the 
mouth of the artery where it ought to go, but 
also back again into the mouth of the vein from 
which it flowed. In Uke manner, when by the 
¥elaxatk)n of the fibres the same cavity is dilated, 
the blood would not only run into it from the 
vein, which was the course intended, but back 
from the artery, through which it ought to be 
moving forward. The way of preventing a reflux 
of the fluid, in both these cases, is to fix valves, 
which, like flood-gates, may open a way to the 
stream in one direction, and shut up the passage 
against it in another. The heart, constituted as 
it is, can no more work without valves than a 
pump can. When the piston descends in a pump, 
if it were not for the stoppage by the valve be- 
neath, the motion would only thrust down the 
water which it had before drawn up. A similar 
consequence would frustrate the action of the 
heart. Valves, therefore, properly disposed, i.e., 
properly with respect to the course of the blood 
which it is necessary to promote, are essential to 



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200 14ATURAL THEOLOGY. 

the contrivance. And valves so disposed are 
accordingly provided. A valve is placed in the 
communication between each auricle and its ven- 
tricle, lest, when the ventricle contracts, part of 
the blood should get back again into the auricle, 
instead of the whole entering, as it ought to do; 
the mouth of the artery. A valve is also fixed at 
the mouth of each of the great arteries which take: 
the blood from the heart; leaving the passage 
free, so long as the blood holds its proper course 
forward ; closing it, whenever the blood, in con- 
sequence of the relaxation of the ventricle, would 
attempt to flow back. There is some variety in 
the construction of these valves, though all the 
valves of the body act nearly upon the same prin- 
ciple, and are destined to the same use. In gene- 
ral they consist of a thin membrane, lying close 
to the side of the vessel, and consequently allow- 
ing an open passage while the stream runs one 
way, but thrust out from the side by the fluid 
getting behind it, and opposing the passage of 
the blood, when it would flow the other way. 
Where more than one membrane is employed, 
the different membranes only compose one valve. 
Their joint action fulfils the office of a valve : for 
instance ; over the entrance of the right auricle 
of the heart into the right ventricle, three of these 
skins or membranes are fixed, of a triangular 



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NATURAL THEOLOGY. 201 

figure^ the bases of the triangles fastened to the 
flesh; the sides and summits loose ; but^ though 
loose, connected by threads of a determinate 
length, with certain small fleshy prominences 
adjoining. The effect of this construction is, 
that, when the ventricle contracts, the blood 
endeavouring to escape in all directions, and 
amongst other directions pressing upwards, gets 
between these membranes and the sides of the 
passage ; and thereby forces them up into such a 
position, as that together they constitute, when 
raised, a hollow cone (the strings before spoken 
of hindering them from proceeding or separating 
farther) ; which cone, entirely occupying the pas- 
sage, prevents the return of the blood into the 
auricle. A shorter account of the matter may be 
this : so long as the blood proceeds in its proper 
coiu^e, the membranes which compose the valve 
we pressed close to the side of the vessel, and 
occasion no impediment to the circulation : when 
the blood would regurgitate, they are raised from 
the side of the vessel, and, meeting in the middle 
of its cavity, shut up the channel. Can any one 
doubt of contrivance here ; or is it possible to 
shut our eyes against the proof of it?** 

^ We cannot resist following up these observations 
with some minute notices of tlie appropriate strocture. 

k3 



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202 NATOKAL THEOLOGY. 

This ralve, also, is not more cnrioos in its »truc- 
tnre, than it is important in its oflSce. Upon the 



Asft^ distended with the wind would be torn up, were not 
the margins secured : aGCordinglyy the canvass is folded 
over a strong cord, which is called the bolt-rope. So 
the margins of these semi-lunar valves are as finely 
finished as any sheet firom the dock-yard. There is a 
hgament which runs along the margin, and strengthens 
it to sustain the impulse of the back-stroke of the artery. 
And were those cordte tendinetB, which we have de- 
scribed as like the leeches of a sail, attached to the 
comer of the mitral valve without finrther security, they 
would be torn off on the first pulsation. But as the 
leeches are secured to the bolt-ropes of the sail, so are 
the cordis iendinem continued into firm hgamentous 
cords which strengthen the valves. 

Our author says well, that the valve is thrown down 
on the side of the artery when the blood is in its course. 
But were this really the case, the refluent blood would 
not easily catch the edge of the valve to throw it up. 
Now this difficulty is met very curiously, and in two dif- 
ferent modes. The cord<B tendinece prevent the mar- 
gins of the mitral valve within the ventricle firom flap- 
ping close against the side of the cavity ; and as to the 
semi^-lunar valves, at the root of the great artery, they 
are prevented falling against the walls in another mode : 
the section of the artery at its root is not a regular circle ; 
but it is formed into three little bags or sinuses, and as 
each of the three valves has a little sinus behind it, its 



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NATURAL THEOLOGY. 203 

play of the valve^ even upon the proportional 
length of the strings or fibres which check the 

margin never reaches the wall of the artery. The con- 
sequence of which is, that in the instant that the column 
of blood takes a retrograde direction, the margins of the 
valve are canght, and they are thrown up to close the 
passage. Nothing can be more admirably mechanical. 




Since our author has so properly insisted upon the 
mechanism of the heart as the very strength of his argu- 
ment, we shall mention one circumstance more as show- 
ing what may be called the perfection of the workmanship. 
It has been explained that the valves of the great artery 
consist of three 8emicii:cular membranes. Now if we 
consider the effect of these three semicircles meeting, 
there must be a triangular space in their centre, an im- 
perfection in the point of their union as it were. To 
remedy this defect, on the centre of the margin of each 
valve, there is a little body like a small excrescence or 
tongue : and when these three bodies meet, they exactly 
fill up the triangular space which is left in the centre of 



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204 NATURAL THEOLOGY. 

ascent of the membranes, depends, as it shoidd 
seem, nothing less than the life itself of the 
animal. We may here likewise repeat, what we 
before observed concerning some of the ligaments 
of the body, that they could not be formed by any 
action of the parts themselves. There are cases 
in which, although good uses appear to arise from 
the shape or configuration of a part, yet that 
shape or configuration itself may seem to be pro- 
duced by the action of the part, or by the action 
or pressure of adjoining parts. Thus the bend 
and the internal smooth concavity of the ribs may 
be attributed to the equal pressure of the soil 
bowels ; the particular shape of some bones and 
joints, to the traction of the annexed muscles, or 
to the position of contiguous muscles. But valves 
could not be so formed. Action and pressure are 
all against them. The blood, in its proper course, 
has no tendency to produce such things ; and in 
its improper or reflected current has a tendency 
to prevent their production. Wliilst we see, 
therefore^ the use and necessity of this machinery, 
we can look to no other account of its origin or 
formation than the intending mind of a Creator. 

the three semicircles. It is as if an ingenious workman 
had contrived a thing the most apposite to remedy a 
defect. 



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NATURAL THEOLOGY. 205 

Nor can we without admiration reflect, that such 
thin membranes, such weak and tender instru- 
ments, as these valves are, should be able to hold 
out for seventy or eighty years. 

Here also we cannot consider but with grati- 
tude, how happy it is that our vital motions are 
involuntary. We should have enough to do, if 
we had to keep our hearts beating and our 
stomachs at work. Did these things depend, we 
will not say upon our effort, but upon our bidding, 
our care, or our attention, they would leave us 
leisure for nothing else. We must have been 
continually upon the watch, and continually in 
fear ; nor would this constitution have allowed of 
sleep. 

It might perhaps be expected, that an organ 
so precious, of such central and primary import- 
ance as the heart is, should be defended by a 
case. The fact is, that a membranous purse or 
bag, made of strong, tough materials, is provided 
for it ; holding the heart within its cavity ; sitting 
loosely and easily about it; guarding its sub- 
stance, without confining its motion; and con- 
taining likewise a spoonful or two of water, just 
sufficient to keep the surface of the heart in a 
state of suppleness and moisture. How should 
such a loose covering be generated by the action 
of the heart ? Does not the enclosing of it in a 



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206 NATURAL THEOLOGY. 

ladc^ answering no otl^ purpose but that endo- 
sure, show the care that has been taken of its jve- 
serration? 

One use of the circulation of tl» Uood probably 
(amongst other uses) is, to distribute nourish- 
ment to the different parts of the body. How 
minute and multiplied the ramifications of the 
blood-vessels for that purpose are ; and how 
thickly spread over at least the superficies of the 
body, is proved by the sin^e observation, that 
we cannot prick the point of a pin into the flesh 
without drawing blood, i.e., without finding a 
blood-vessel. Nor internally is their difiusion 
less universal. Blood-vessels run along the sur- 
face of membranes, pervade the substance of 
muscles, penetrate the bones. Even into every 
tooth we trace, through a small hole in the root, 
an artery to feed the bone, as well as a vein to 
bring back the spare blood from it ; both which, 
with the addition of an accompanying nerve, 
form a thread only a little thicker than a horse- 
hair. 

Wherefore, when the nourishment taken in at 
the mouth has once reached and mixed itself 
with the blood, every part of the body is in the 
way of being supplied with it. And this intro- 
duces another grand topic, namely, the manner 
in which the aliment gets into the blood; which 



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NATURAL THEOLOGY. 207 

is a subject distinct from the preceding, and 
brings us to the eoninderaticm of another entve 
system of ve«»ls. 

III. For this necessary part of the animal 
economy an ajqparatus is provided in a great 
measure capable of being what anatomists call 
demonstrated^ that is^ shown in the dead body; 
tmd a line or course <^ conveyance, which we can 
pursue by our ^caminations. 

First, the food descends by a wide passage into 
^be intestines, umfergoing two great preparations 
on its way : one in the mouth by mastication and 
moisture — (can it be doubted with what design 
the teeth were ipiBced in the road to the stomach, 
or that there was choice in fixing them in this 
situation?) — ^the other by digestion in the sto- 
mach itself. Of this last surprising dissolution 
I say nothing ; because it is chemistry, and I am 
endeavouring to display mechanism. The figure 
and position of the stomach (I speak all along 
with a reference to the human organ) are calcu- 
lated for detaining the food long enough for the 
action of its digestive juice. It has the shape 
of the pouch of a bagpipe ; lies across the body ; 
and the pylorus, or passage by which the food 
leaves it, is somewhat higher in the body than the 
cardia or orifice by which it enters; so that it is 
by the contraction of the muscular coat of the 



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208 NATURAL THEOLOGY, 

stomach that the contents, after having under- 
gone the application of the gastric menstruum, are 
gradually pressed out In dogs and cats, this 
action of the coats of the stomach has been dis- 
played to the eye. It is a slow and gentle undu- 
lation, propagated from one orifice of the sto- 
mach to the other. For the same reason that I 
omitted, for the present, offering any observation 
upon the digestive fluid, I shall say nothing con- 
cerning the bile or the pancreatic juice, further 
than to observe upon the mechanism, viz., that 
from the glands in which these secretions are ela- 
borated pipes are laid into the first of the inte»T 
tines, through which pipes the product of each 
gland flows into that bowel, and is there mixed 
with the aliment as soon almost as it passes the 
stomach ; adding also as a remark, how grievously 
this same bile offends the stomach itself, yet che- 
rishes the vessel that lies next to it. 

Secondly. We have now the aliment in the in- 
testines converted into pulp; and though lately 
consisting of ten different viands, reduced to 
nearly a uniform substance, and to a state fitted 
for yielding its essence, which is called chyle, but 
which is milk, or more nearly resembling milk 
than any other liquor with which it can be com- 
pared. For the straining off this fluid from the 
digested aUment in the course of its long progress 



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NATURAL THEOLOGY. 209 

through the body, myriads of capillary tubes, i, e., 
pipes as small as hairs, open their orifices into the 
cavity of every part of the intestines. These 
tubes, which are so fine and slender as not to be 
visible unless when distended with chyle, soon 
unite into larger branches. The pipes formed by 
this union terminate in glands, from which otlier 
pipes, of a still larger diameter, arising, carry the 
chyle from all parts into a common reservoir or 
receptacle. This receptacle is a bag of size enough 
to hold about two table-spoons full ; and from this 
vessel a duct or main pipe proceeds, climbing up 
the back part of the chest, and afterwards creep- 
ing along the gullet till it reach the neck. Here 
it meets the river ; here it discharges itself into a 
large vein, which soon conveys the chyle, now 
flowing along with the old blood, to the heart. 
This whole route can be exhibited to the eye; no- 
thing is left to be supplied by imagination or con- 
jecture. Now, besides the subserviency of this 
structure, collectively considered, to a manifest 
and necessary purpose, we may remark two or 
three separate particulars in it, which show, not 
only the contrivance, but the perfection of it. We 
may remark, first, the length of the intestines, 
which, in the human subject, is six times that of 
the body. Simply for a passage, these volumi- 
nous bowels, this prolixity of gut, seems in no- 



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210 NATURAL THEOLOGY. 

wise necessary; but m order to allow time and 
qmce for the successire extraction of the chyle 
from the digestire aliment, namely, that the chyle 
whidi escapes the lacteals of one part of the guts 
may be taken up by those of some other part, the 
length of the canal is of evident use and con- 
duciveness. Secondly, we must also remark their 
peristaltic motion, which is made up of contrac- 
tions following one another Kke waves upon the 
surface of a fluid, and not unlike what we observe 
in the body of an earthworm crawKng along the 
ground, and which is effected by the joint action 
of longitudinal and of spiral, or rather perhaps 
of a great number of separate semicircular fibres. 
This curious action pushes forward the grosser 
part of the aliment, at the same time that the 
more subtile parts, which we call chyle, are, by a 
series of gentle compressions, squeezed into the 
narrow orifices of the lacteal veins. Thirdly, it 
was necessary that these tubes, which we denomi- 
nate lacteals, or their mouths at least, should be 
made as narrow as possible, in ordet to deny ad- 
mission into the blood to any particle which is of 
size enough to make a lodgment afterwards in the 
small arteries, and thereby to obstruct the circu- 
lation; and it was also necessary that this ex- 
treme tenuity should be compensated by multi- 
tude ; for a large quantity of chyle (in ordinary 



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NATURAL THEOLOGY. 21 1 

ccHistitetions not less> it has been computed, than 
two or three quarts in a day) is, by some means or 
other, to be passed through them. Accordingly, 
we find the number of the lacteals exceeding aU 
powers of ccwnputation, and their pipes so fine and 
slender as not to be visible, unless filled, to the 
naked eye, and their orifices, winch open into the 
intestines, so small as not to be discernible even 
by the best microscope. Fourthly, the main pipe^ 
which carries the chyle from the reservoir to the 
blood, viz., the thoracic duct, being fixed in an 
almost upright position, and wanting that advan- 
tage of propulsion which the arteries possess, is 
nimished with a succession of valves to check the 
ascending fluid, when once it has passed them, 
from falling back. These valves look upwards, 
so as to leave the ascent free, but to prevent the 
return crfthe chyle, if, for want of sufficient force 
to push it on, its weight should at any time cause 
it to descend. Fifthly, the chyle enters the blood 
in an odd place, but perhaps the most commo- 
dious place possible, viz., at a large vein in the 
neck, so situated with respect to the circulation as 
speedily to baring the mixture to the heart. And 
this seems to be a circumstance of great moment ; 
for had the chyle entered the blood at an artery, 
or at a distant vdn, the fluid composed of the old 
and the new materials must have performed a consi- 



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212 NATURAL THEOLOGY. 

derable part of the circulation before it received 
that churning in the lungs which is probably ne- 
cessary for the intimate and perfect union of the 
old blood with the recent chyle. Who could have 
dreamt of a communication between the cavity of 
the intestines and the left great vein of the neck ? 
Who could have suspected that this communica- 
tion should be the medium through which all nou- 
rishment is derived to the body, or this the place 
where, by a side inlet, the important junction is 
formed between the blood and the material which 
feeds it ? 

We postponed the consideration of digestion, 
lest it should interrupt us in tracing the course of 
the food to the blood; but in treating of the ali- 
mentary system, so principal a part of the process 
cannot be omitted. 

Of the gastric juice, the immediate agent by 
which that change which food undergoes in our 
stomachs is effected, we shall take our account 
from the numerous, careful, and varied experi- 
ments of the Abb^ Spallanzani. 

1. It is not a simple diluent, but a real solvent. 
A quarter of an ounce of beef had scarcely touched 
the stomach of a crow, when the solution began. 

2. It has not the nature of saliva ; it has not 
the nature of bile ; but is distinct from both. By 
experiments out of the body, it appears that nei- 



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NATURAL THEOLOGY. 213 

tlier of these secretions acts upon alimentary sub- 
stances in the same manner as the gastric juice 
acts. 

3. Digestion is not putref actum; for the digest- 
ing fluid resists putrefaction most pertinaciously ; 
nay, not only checks its farther progress, but re- 
stores putrid substances. 

4. It is not a /ermenfa^iue process; for the solu- 
tion begins at the surface, and proceeds towards 
the centre, contrary to the order in which fer- 
mentation acts and spreads. 

5. It is not the digestion of heat ; for the cold 
maw of a cod or sturgeon will dissolve the shells 
of crabs or lobsters, harder than the sides of the 
stomach which contains them. 

In a word, animal digestion carries about it 
the marks of being a power and a process com- 
pletely 8ui generis, distinct from every other, at 
least from every chemical process with which we 
are acquainted. And the most wonderful thing 
about it is its appropriation — ^its subserviency to 
the particular economy of each animal. The gas- 
tric juice of an owl, falcon, or kite will not touch 
grain ; no, not even to finish the macerated and 
half-digested pulse which is left in the crops of 
the sparrows that the bird devours. In poultry, 
the trituration of the gizzard, and the gastric 
juice, conspire in the work of digestion. The 



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214 NATURAL THEOLOGY. 

gastric juke will not dissolve the grain whilst it is 
whole. Entire grains of barley^ enclosed in tubes 
or spherules, are not affected by it. But if the 
same grain be by any means broken or ground, 
the gastric juice immediately lays hold of it. 
Here then is wanted, and here we find, a combi- 
nation of mechanism and chemistry**. For the 
preparatory grinding the gizzard lends its mill ; 
and as all mill-work should be strong, its struc- 
ture is so beyond that of any other muscle bdong- 
ing to the animal. The internal coat also, (»r 
lining of the gizzard, is, for the same purpose, 
hard and cartilaginous. But, forasmuch as this 
is not the sort of animal substance suited for the 
reception of glands, or for secretion, the gastric 
juice, in this family, is not supplied, as in mem- 
branous stomachs, by the stomach itself, but by 
the gullet, in which the feeding-glands are placed, 
and from which it trickles down into the stomach. 
In sheep, the gastric fluid has no effect in di- 
gesting plants, unless they have been previously 
masticated. It only produces a slight maceration, 
nearly such as common water would produce^ in a 

** One of the many modes by which seeds are carried 
to a distance, and Sir Joseph Banks gave us reason to 
belieTe that it served as a preparation for sowing, as 
seeds so carried germinated socmer. 



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NATURAL THEOLOGY. 215 

degree of heat somewhat exceeding, the medium 
temperature of the atmosphere. But, provided 
that the plant has been reduced to pieces by 
chewing, the gastric juice then proceeds with it, 
first, by softening its substance ; next, by destrc^- 
ing its natural consistency ; and, lastly, by dis- 
solving it so completely as not even to spare the 
toughest and most stringy parts, such as the 
nerves of the leaves. 

So far our accurate and indefatigable Abb^. 
Dr. Stevens, of Edinburgh, in 1777, found, by 
experiments tried with perforated balls, that ihe 
gastric juice of the sheep and the ox speedily dkh 
.s<dved vegetables, but made no impression upon 
beef, mutton, and other animal bodies. Mr. 
Hunter discovered a property of this fluid, of a 
most curious kind — ^viz., that in the stomachs of 
animals which feed upon flesh, irresistibly as this 
.fluid acts upon animal substances, it is only upon 
the dead substance that it operates at alL The 
living fibre suffers no injury from lying in contact 
with it. Worms and insects are found aUve in 
the stomachs of sudi animals. The coats of the 
human stomach, in a healthy state, are iusaisible 
to its presence ; yet in cases of sudden death 
(wherein the gastric juice, not having been weak- 
ened by disease, retains its activity), it has been 
known to eat a hole through the bowel which 



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216 NATURAL THEOLOGV. 

contains it'*'. How nice is this discrimination of 
action^ yet how necessary ! 

But to return to our hydraulics. 

IV. The gall-bladder is a very remarkable con- 
trivance. It is the reservoir of a canal. It does 
not form the channel itself — f. e., the direct com- 
munication between the liver and the intestine^ 
which is by another passage — ^viz., the ductus 
hepaticus, continued under the name of the ductus 
communis; but it lies adjacent to this channel^ 
joining it by a duct of its own, the ductus cysticus : 
by which structure it is enabled, as occasion may 
require, to add its contents to and increase the 
flow of bile into the duodenum. And the posi- 
tion of the gall-bladder is such as to apply this 
structure to the best advantage. In its natural 
situation, it touches the exterior surface of the 
stomach, and consequently is compressed by the 
distention of that vessel : the effect of which com- 
pression is to force out from the bag, and send 
into the duodenum, an extraordinary quantity of 
bile, to meet the extraordinary demand which the 
repletion of the stomach by food is about to 
occasiont. Cheselden describes^ the gall-bladder 
as seated against the duodenum, and thereby 
liable to have its fluid pressed out by the passage 

* Phil. Trans. Yol. Ixii. p. 447. f KeilPs Anat. p. 64. 
' X Anat. p. 164. 



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NATURAL THEOLOGY, 217 

of the aliment through that cavity, which likewise 
will have the effect of causing it to be received 
into the intestine at a right time and in a due 
proportion* 

There may be other purposes answered by this 
contrivance, and it is probable that there are. 
The contents of the gall-bladder are not exactly 
of the same kind as what passes from the liver 
through the direct passage*. It is possible that 
the gall may be changed, and for some purposes 
meUorated, by keeping**. 

The entrance of the gall-duct into the duode- 
num furnishes another observation. Whenever 
either smaller tubes are inserted into larger tubes, 
or tubes into vessels and cavities, such receiving 
tubes, vessels, or cavities, being subject to muscu- 
lar constriction, we always find a contrivance to 
prevent regurgitation. In some cases valves are 
used; in other cases, amongst which is that now 
before us, a different expedient is resorted to, 
which may be thus described : the gall-duct en- 
ters the duodenum obliquely ; after it has pierced 

^ On this passage some remarks on the absence of 
the gall-bladder in certain animals might be required ; 
but the reader may turn to the note in the Appendix 
on the stomach of the horse. 

* Keill (from Alalpighius), p. 63. 

L 



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218 NATURAL theology; 

the first cozt, it runs near two fingers* breadth 
between the coats before it opens into the cayity of 
the intestine*. The same contrirance is used in 
another part^ where there is exactly the same 
occasion for it> viz.> in the insertion of the ureters 
in the bladder. These enter the bladder near its 
neck^ running obliquely for the space of an inch 
between its coatsf . It ia, in both cases^ suflSi- 
ciently evident that this structure has a necessary 
mechanical tendency to resist regurgitation ; for 
whatever force acts in such a direction as to urge 
the fluid back int6 the orifices of the tubes^ must^ 
at the same time, stretch the coats of the vessels^ 
and thereby compress that part of the tube which 
is included between them* 

V. Amongst the vesteh of the human body, the 
pipe which conveys the sdiiva firom the phice where 
it is made to the place where it is wanted deserves 
io be reckoned amongst the most intelhgibEe pieces 
of mechanism with which we are acquainted* The 
fiahva, we all know, is used in the mouth; but 
inuch of it is produced on the outside of the.ched^ 
Jby-^the psurotid gland, which lies- between the ear 
^d the angle of the k>wer jaw. In order to carry 
the secreted juice to ita. destinatioii, there is lai^ 
£rom the gland on the outside a pipe. alxH^t the 

* KeiU's AMi. p. 62. i^ CM*. Anat. p. 260. 



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"natural theologt. 219 

thickness, of a wheat straw, and about three fin^ 
gers' Iwreadth in length, which, after riding over 
the masseter muscle, bores for itself a hole through 
tl^ very middle of the cheek, enters by that hole, 
which is a complete perforation of the buccinator 
fliuscle, into the mouth, and there discharges its 
fluid very copiously. 

VI. Another exquisite structure, difiFering, in- 
deed, from the four preceding instances in that it 
does not relate to the conveyance of fluids, but 
still belonging, like these, to the class of pipes or 
conduits of the body, is seen in the larynx. We 
all know that there go down the throat two pipes, 
one leading to the stomach, the other to the lungs 
— ^the one being the passage for the food, the 
other for the breath and voice: we know also^ 
that both these passages open into the bottom of 
the mouth — the gullet, necessarily, for the con- 
veyance of food, and the wind^pipe, for speech and 
the modulation of sound, not much less so : there- 
fore the difficulty was, the passages being* so con- 
tiguous, to prevent the food, especially the Kquidsf, 
which we swallow into the stomach from entering 
ite wind-pipe, i, e., the road to the lungs— the 
consequence of which error, when it does happ€ii> 
is p^ceived by the convulsive throes th^t are vtt- 
«lantly produced. This business, which is very 
nice, j» managed in this nwrnner. TheguUet{tlie 

l2 



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220 NATURAL THEOLOGY. 

passage for food) opens into the mouth like the 
cone or upper part of a funnel^ the capacity rf 
which forms indeed the bottom of the mouth. 
Into the side of this funnel, at the part which lies 
ihe lowest, enters the wind-pipe by a chink or 
slit, mth a lid or flap, Uke a little tongue, accu- 
rately fitted to the orifice. The soUds or liquids 
which we swallow pass over this lid or flap as they 
descend by the funnel into the gullet. Both the 
weight of the food and the action of the muscles 
concerned in swallowing contribute to keep the 
lid close down upon the aperture whilst anything 
is passing ; whereas, by means of its natural carti- 
laginous spring, it raises itself a little as soon as 
the food is passed, thereby allowing a free inlet 
and outlet for the respiration of air by the lungs. 
Such is its structure ; and we may here remark 
the almost complete success of the expedient, viz., 
how seldom it fails of its purpose compared with 
the number of instances in which it fulfils it. Re- 
flect how frequently we swallow, how constantly 
we breathe. In a city-feast, for example, what 
deglutition, what anhelation ! yet does this little 
cartilage, the epiglottis, so effectually interpose 
its office, so securely guard the entrance of the 
wind-pipe, that whilst morsel after morsel, draught 
after draught, are coursing one another over it> 
an accident of a crumb or a drop slipping into 



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NATURAL THEOLOGY* 221 

this passage (which, nevertheless, must be opened 
for the breath every second of time), excites in the 
whole compai^, not only alarm by its danger, but 
surprise by its novelty. Not two guests are 
choked in a century. 

There is no room for pretending that the action 
of the parts may have gradually formed the epi* 
glottis : I do not mean in the same individual, 
but in a succession of generations. Not only the 
action of the parts has no such tendency, but the 
animal could not live, nor consequently the parts 
act, either without it or with it in a half-formed 
state. The species was not to wait for the gra* 
dual formation or expansion of a part which was 
from the first necessary to the life of the indi- 
vidual. 

Not only is the larynx curious, but the whole 
wind-pipe possesses a structure adapted to its 
peculiar office. It is made up (as any one may 
perceive by putting his fingers to his throat) of 
stout cartilaginous ringlets, placed at small and 
equal distances from one another. Now this is 
not the case with any other of the numerous con- 
duits of the body. The use of these cartilages is 
to keep the passage for the air constantly open, 
which they do mechanically. A pipe with soft 
membranous coats, liable to collapse and close 
when empty, would not have answered here; 



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222 VATURAL THEOLOGY. 

althongli this be the general vauBoular strnctuie, 
and a staructore which serves very well for those 
tubes which are kept in a state of parpetoal dis- 
tention by the #uid they enclose^ or whidi afford 
a passage to solid and protnubig substances. 

Nevertheless (which is another particularity 
weU worthy of notice)^ these rings are not com* 
plete — ^thatis, are not cartilaginous and stiff all 
round ; but their hinder part, which is contiguous 
to the gullet, is membranous and soft, easily 
yielding to the distentions of that organ ooca^ 
sioned by the descent of solid food. The same 
rings are also bevelled off at the upper and lower 
edges, the better to close upon one another when 
ihe trachea is compressed or shortened. 

The constitution of the trachea may suggaH; 
likewise another reflection. The membrane which 
lines its inside is perhaps the most sensible, irri- 
table membrane of the body. It rejects the touch 
of a crumb of bread, or a drop of water, with a 
spasm which convulses the whole frame ; yet, left 
to itself and its proper office, the intromission of 
air alone, nothing can be so quiet. It does not 
«ven make itself felt ; a man does not know that 
he has a trachea. This capacity of perceiving witfi 
such acuteness, this impatience of offence, yet pot- 
feet rest and ease when let alone, are propertied, 
one would have thought, not likely to reside in 



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KATDRAL TUfiOLOOT. 223 

the same* sul^t. It is to ihe junctiim, however, 
of these almost inconsistent qualities^ in diis, as 
well as in some other delicate parts of the hodj; 
that we owe our safety and our comfort — our 
safety to their sensibility, our comfort to their 
repose". 

** Our author tooches here upon the senedbilities 
whidi govern the motkms of the chest — a subject whidi 
might be enlarged upon to fill a volume. But consider* 
ing the object of this woik, we ought not to omit the 
t>ccmon of observing the union of a property of life with 
the most complex mechanical structure imaginable 
We have seen, in former notes, that fot the grand and 
vital purpose of decarboniziug the blood, the atmospherio 
air must be drawn deep into the lungs ; and the pro- 
blem is, to permit the vital air to pass^ and yet prevent 
foreign matter from finding access. On this subject 
there is a note in the Appendix. But the more remark- 
able circumstance in connexion with the statement in 
the text is, that the whole of this apparatus for respira- 
tion is taken fiom the governance of the will, and placed 
under a power more constantly vigilant and more abso* 
ktely peremptory. The sensibility about tbe glottis 
holds in control an hundred muscles; and whilst it 
excites the action, directe the force of tbe stream ci 
expired air with extraor^toary exactness to the very 
pwnt where iJie hrriUting matter lodges, be it in H^ 
passages of the throat, or in tbe cavities of the nose. 



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224 NATURAL THEOLOGY. 

The larynx, or rather the whole wind-pipe taken 
together (for the larynx is only the upper part of 
the wind-pipe), besides its other uses, is also a 
musical instrument — ^that is to say, it is mechanism 
expressly adapted to the modulation of sound ; 
for it has been found upon trial, that, by relaxing 
or tightening the tendinous bands at the extre-^ 
mity of the wind-pipe, and blowing in at the other 
end, all the cries and notes might be produced of 
which the living animal was capable. It can be 
sounded just as a pipe or flute is sounded. 

Birds^ says Bonnet, have, at the lower end of 
the windpipe, a conformation like the reed of a 
hautboy, for the modulation of their notes. A 
tuneful bird is a ventriloquist. The seat of the 
song is in the breast. 

The use of the lungs in the system has been 
said to be obscure; one use, however, is plain, 
though, in some sense, external to the system. 

There are many instances of the same kind in the eco- 
nomy of the frame, where actions are excited by sensi- 
bilities seated in certain spots, some of them attended 
with suflFering, by which our voluntary efforts are brought 
in aid, and others where there is neither sensation nor 
volition, and yet the muscles are controlled and regu« 
lated, and the oflSces performed, with undeviating preci- 
sion. 



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NATURAL THEOLOGT^ 225 

and that is, the formation, in conjunction with 
the larynx, of voice and speech. They are, to 
animal utterance, what the bellows are to the 
organ.** 



For the sake of method, we have considered 
animal bodies under three divisions : their 
bones, their muscles, and their vessels ; and we 
have stated our observations upon these parts 
separately,. But this is to diminish the strength 
of the argument. The wisdom of the Creator is 
seen, not in their separate but their collective 
action; in their mutual subserviency and de- 
pendence; in their contributing together to one 
effect and one use. It has been said, that a man 
cannot lift his hand to his head without finding 
enough to convince him of the existence of a God. 
And it is well said ; for he has only to reflect, 
familiar as this action is, and simple as it seems 
to be, how many things are requisite for the per- 
forming of it ; how many things which we under* 
stand, to say nothing of many more, probably, 
which we do not : viz.> first, a long, hard, strong 

** The subject admits of a much more extensive ap* 
plication of physical science ; and one division of it will 
be found treated in the Appendix. 

l3 



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226 KATURAL THBOLOOY. 

tyhnder, in order to give to the arm its firmnesn 
and tension ; but whidi, being rigid, and, in its 
fmbstanoe, inflexible, can only turn up<m joints ; 
secondly, therefore, joints for this purpose ; one 
at the shoulder to raise the arm, another at the 
elbow to bend it; these joints continually fed 
with a soft mndlage to make the parts slip easily 
tipon one another, and holden together by strong 
braces, to ke^ them in their position : then, 
thirdly, strings and wires — t. e., muscles and ten- 
dons — artificially inserted, for the purpose of 
drawing the bones in the directions in which the 
joints allow them to move. Hitherto we seem to 
understand the mechanism pretty well ; and, un* 
derstanding this, we possess enough for our con^ 
elusion : Nevertheless, we have hitherto only a 
machine standing still — a dead organization — an 
apparatus. To put the system in a state of ac« 
tivity, to set it at work, a fiirther provimon is 
necessary — ^viz., a communication with the brain 
by means of nerves. We know the existence of 
-tins communication, because we can see the com- 
.municating threads, and can trace them to the 
;brain : its necessity we also know, because if the 
thread be cut, i£ the communicatian be inter- 
cepted, the muscle becomes parsdytic ; but beyond 
.this we know little, the organization being too 
minute and subtile for our inspectioin. 



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•"^^^^mgm^mm 



To what has been enumerated, as officiating in 

the single act of a man's raising his hand to his 

head, must be added hkewise all that is necessary 

^^^ all that contributes to the growth, nourish- 

]°?ent, and sustentation of the limb, the repair of 

waste, the preservation of its health : such as 

™« circula4iQii of the Uood through every part 

^^ it; its lymphatics, eihalents, absorbents; its 

^etioBs and integuments. All these share in 

*he i^estdt— ^oixi ia the ^ect; and how all these, 

w any bf thein, come together without a design- 

***& disposing^ intellieence, it is impassible to 

<JoiKJeive. 



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228 NATURAL THBOLOOT. 



CHAPTER XI. 

OF THE ANIMAL STRUCTURE REGARDED AS A MASS. 

CoNTEMPLATiKo ait afumal body in its collective 
capacity^ we cannot forget to notice what a num« 
ber of instruments are brought together^ and 
often within how small a compass. It is a cluster 
of contrivances. In a canary-bird^ for instance, 
and in the single ounce of matter which composes 
his body (but which seems to be all employed), 
we have instruments for eatings for digesting^ for 
nourishment^ for breathings for generation, for 
running, for flying, for seeing, for hearing, for 
smelling: each appropriate — each entirely dif- 
ferent from all the rest. 

The human or indeed the animal frame, consi- 
dered as a mass or assemblage, exhibits in its 
composition three properties, which have long 
struck my mind as indubitable evidences not only 
of design, but of a great deal of attention and 
accuracy in prosecuting the design. 

I. The first is, the exact correspondency of the 
two sides of the same animal: the right hand 
answering to the left, leg to leg, eye to eye, one 
side of the countenance to the other; and with a 



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NATURAL THEOLOGT, 229 

precision, to imitate which in any tolerable de- 
gree forms one of the diflELculties of statuary, and 
requires, on the part of the artist, a constant at- 
tention to this property of his work, distinct from 
every other. 

It is the most difficult thing that can be to get 
a wig made even ; yet how seldom is the face 
awry ! And what care is taken that it should not 
be so, the anatomy of its bones demonstrate£i. 
The upper part of the face is composed of thirteen 
bones, six on each side, answering each to each^ 
and the thirteenth, without a fellow, in the middle. 
The lower part of the face is in like manner com- 
posed of six bones, three on each side, respectively 
corresponding, and the lower jaw in the centre. 
In building an arch, could more be done in order 
to make the curve true — i.e., the parts equi- 
distant from the middle, alike in figure and posi- 
tion ? 

The exact resemblance of the eye«, considering 
how compounded this organ is in its structure, 
how various and how delicate are the shades of 
colour with which its iris is tinged ; how differ- 
ently, as to effect upon appearance, the eye may 
be mounted in its socket, and how differently in 
different heads eyes actually are set — ^is a pro* 
perty of animal bodies much to be admired* Of 
ten thousand eyes, I do not know that it would 



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230 JTAtURAL THBOLOOT. 

be possible to maJtch one, elcept wilh iCs own 
feUow; or to distribute tbcm into suitable pairs 
by any other selection than tbat which obtains. 

This regularity of the animal t^tnu^uvc is len^ 
dered more remarkable by the three following 
eofisiderations :•— 

1. The limbs, separately taken, luiTe not this 
correlation of parts, but the contrary of it A 
knife drawn down the chine cuts the human body 
into two parts, externally equal and alike; yotl 
cannot draw a straight line whidi will diride a 
hand, a foot, the leg, the thigh, the cheek, the 
Bye, the eat, into two parts equal and alike: 
Those parts which are placed upon the middle oir 
partition fine of the body, or which trarerse that 
line — as the nose, the tongue, and the lips — may 
-be so divided, or, more properly speaking, are 
double organs; but other parts cannot. This 
shows that the correspondency which we have 
been describing does not arise by ainy necesedty 
in the nature of the subject; for, if necessary, it 
would be universal ; whereas it is observed only 
in the system or ass^nblage* It is not true of 
the separate parts : that is to say> it is found 
where it conduces to beauty or ^utility; it is not 
fcund where it would subsist at the expense of 
both. The two wii^ of a bird always corre^ 
spend : the two sides- of a feath^ frequei^y do 



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JTATtmAL THEOLOGY. 231 

not. In centipedes, millepedes, and the whole 
tribe of insects, no two legd on the same side ane 
alike ; yet tha*e is the most exact parity between 
the legs opposite to one another. 

2. The next ciri^um^tance to be remarked is, 
that, whilst the cavities of the body are so confi- 
gurated, as externally to exhibit the most exact 
correspondency of the opposite sides, the contend 
i^ these cavities have no such correspondency. A 
line drawn down the middle of the breast divide 
the thorax into. two sides exactly sbpilar; yet 
.these two sid^ enclose very different cont^its. 
.The heart lies on the left side; a lobe of the 
lungs on the right ; balancing each other neither 
in size nor shape. The same thing holds of tJae 
abdc»nen. The liver lies on tte right side, with- 
out any similar viscus opposed to it on the left. 
The spleen indeed is atuated over-against the 
liver ; but agreeing with the Uver neither in bulk 
Bor form. There is no equipoUency between 
: these. The stomach is a vessel^ both irregular 
in its shape, and oblique in its position. The 
foldings and doublings of the intestines do not 
presaoi a parity df sides. Yet that symmetry 
which depends upon the correlation of the sides 
is externally preserved throughout the whole 
trunk; and is the more remarkable in the lower 
rparts cf it, as the integum^ats are soft; and the 



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232 NATURAL THEOLOGY. 

shape^ consequently^ is not, as the thorax is by its 
ribs, reduced by natural stays. It is evident, 
therefore, that the external proportion does not 
arise from any equality in the shape or pressure 
of the internal contents. What is it, indeed, 
but a correction of inequalities ? — an adjustment, 
by mutual compensation, of anomalous forms into 
a regular congeries ? — ^the effect, in a word, of art- 
ftd, and, if we might be permitted so to speak, of 
studied collocation ? 

3. Similar also to this is the third observation : 
that an internal inequality in the feeding vessels 
is so managed as to produce no inequality of parts 
which were intended to correspond. The right 
arm answers accurately to the left, both in size 
and shape ; but the arterial branches which sup- 
ply the two arms do not go off* from their trunk, 
in a pair, in the same manner, at the same place, 
or at the same angle. Under which want of simi- 
litude, it is very difficult to conceive how the same 
quantity of blood should be pushed through each 
artery ; yet the result is right ; the two limbs 
which are nourished by them perceive no dif- 
ference of supply— no effects of excess or defi- 
ciency. 

Concerning the difference of manner in which 
the subclavian and carotid arteries, upon the dif- 
ferent sides of the body, separate themselves from 



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NATURAL THEOLOGY* 233 

the aiirta^ Cheselden seems to have thought, that 
the advantage which the left gain by going off at 
an angle much more acute than the right, is made 
up to the right by their going off together in one 
branch*. It is very possible that this may be the 
compensating contrivance ; and if it be so, how 
curious — how hydrostatical ! 

II. Another perfection of the animal mass is 
the package, I know nothing which is so sur- 
prising. Examine the contents of the trunk of 
any large animal. Take notice how soft, how 
tender, how intricate they are ; how constantly in 
action, how necessary to life ! Reflect upon the 
danger of any injury to their substance, any de- 
rangement of their position, any obstruction to 
their office. Observe the heart pumping at the 
centre, at the rate of eighty strokes in a minute ; 
one set of pipes carrying the stream away from it, 
another set bringin'g, in its course, the fluid back 
to it again ; the lungs performing their elaborate 
office, viz., distending and contracting their many 
thousand vesicles by a reciprocation which can- 
not cease for a minute ; the stomach exercising 
its powerfiil chemistry; the bowels silently pro- 
pelling the changed aliment ; collecting from it, 
as it proceeds, and transmitting to the blood an 
incessant supply of prepared and assimUated nou- 
• Ches. Anat. p. 184. ed. 7,. 



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234 2f ATURAL THKOLOCnr. 

rkliment; fliat hlood pomui^ its coune; the 
Inrer^ the kidneys, the pancreas, the parotid, with 
many other known and distingaishahle glands, 
drawing off from it, all the while, dieir proper 
secretions. Hiese seraral operations, together 
with others more subtile but less capable of being 
investigated, are going on within us at one and 
the same time. Tliink of this ; and then obs^re 
how the body itself, the case which holds this ma- 
chinery, is rolled, and jolted, and tossed about, 
the mechanism remaining unhurt, and with Tery 
little molestation even of its nicest motions. 
Observe a rope-dancer, a tumbler, or a m<mkey ; 
die sudden inversions and contortions whidli the 
internal parts sustain by the postures into wfak^ 
their bodies are thrown; or rather observe tiie 
shodks which these parts, even in ordinary sub- 
jects, sometimes receive fix>m fisdls and bruises, or 
by abrupt jerks and twists, without sensible or 
with soon-recovered damage. Observe this, and 
then reflect how firmly every part must be secured, 
how carefully surrounded, how well tied down and 
packed t<^ther. 

This pr<qperty of animal bodies has never, I 
diink, been considered under a distinct head, or 
80 fully as it deserves. I may be allowed there- 
fore, in order to verify my observation concerning 
it, to set forth a short anatomical detail, though 



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If ATXISAL TB^OLOGT. ZHS 

k oUige me to use more ted&nieal language tfaaa 
I sliould vnah to introduce into a work of this 
kind 

1« The heart (svxih care is taken of the centre 
of Hfe) is placed between two scrft lobes of the 
lungs; is tied to the mediastinum and to the 
pericardium ; whidi pericardium is not only itself 
an exceedingly strong membrane^ but adhere^ 
firmly to the duplicature of the mediastinum, and# 
by its point, to the middle tendon of the dia* 
pfaragm. The heart is also sustained in its place 
by the great blood-vessels which issue from it *. 

2. Tlie bmgs axe tied to the sternum by the 
mediastinum before; to the vertebras, by the 
pleura behind It seems indeed to be the very 
use of the mediastinum (which is a membrane 
that goes strai^t through the middle of the 
ihorax, from ihe breast to the back) to keep the 
contents of the thorax in their places ; in par- 
ticular to hinder one lobe of the lungs from in- 
commoding another^ or the parts of the lungs 
ftdm pressing upon eadi other when we lie on 
one side f . 

3. The liver is fastened in the body by two 
ligaments: the first, which is large and strong, 
comes from the covering of the diaphragm, and 
penetrates the substance of the liver; the second 

* KeiU's AbmL p. 107, ed. 3. . t lb. p. U9, «4. 3. 



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236 NATURAL THEOLOGY. 

is the umbilical vein, which, after birth, degene- 
rates into a ligament The first, which is the 
principal, fixes the liver in its situation whilst the 
body holds an erect posture ; the second prevents 
it firom pressing upon the diaphragm when we lie 
down; and both together sling or suspend the 
liver when wo lie upon our backs, so that it may 
not compress or obstruct the ascending vena 
cava*, to which belongs the important office of 
returning the blood from the body to the heart. 

4. The bladder is tied to the navel by the lura* 
chus, transformed into a ligament: thus, what 
was a passage for tirine to the fcetus, becomes, 
after birth, a support or stay to the bladder* 
The peritonaeum also keeps the viscera firom con-^ 
founding themselves \rith, or pressing irregularly 
upon, the bladder; for the kidneys and bladder 
are contained in a distinct dnplicature of that 
membrane, being thereby partitioned oflF from the 
other contents of the abdomen. 

5. The kidneys are lodged in a bed of fat. 

6. The pancreas, or sweetbread, is strongly tied 
to the peritonaeum, which is the great wrapping 
sheet, that encloses all the bowels contained in 
the lower belly f. 

7. The spleen also is confined to its place by an 
adhesion to the peritonaeum and diaphragpn, and 

• Ches. Anat. p. 162. f KeUl's Anat. p. 57. 



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mm 



NATURAL THEOLOGY. 237 

sibJe ''^''^^^'^^ ^th the omentum*. It is pos- 

nierel ^^ ^^ ^V^^on, that the spleen may be 

canc/or h''^'*^' a soft cushion to fiU up a va- 

leave th ^ ^^' which, unless occupied, would 

posing th ^^.^^^^^ ^^^^^ a^^ unsteady : for, sup- 

^* must h ^* ^^®^®^s no other purpose than this, 

^hrouo-i -x . ^^^^ar, and admit of a circulation 

^^a iivin K^ ^^^^^ *^ ^^ ^®P* ^^^' ^^ ^^ ^ P^^^ 

8. T'T| ^" 

"^^cJced u ^^^^'^y epiploon, or cawl, is an apron 

part, "jn^ ' ^^ doubling upon itself, at its lowest 

*ie stonxacdi ^^^^^^ ^^S® ^® *^^^ *^ *^® bottom of 

observed * ^ ^^ spleen, as hath already been 

reflected ed^^ *o part of the duodenum. The 

^omes up |j ?? ^^^^^ after forming the doubling, 

^^^» and aH • ^^^ *^® fr^°* ^ap, and is tied to the 

^joining viseeraf. 



'Ur 



^^ich lies i ^^ ^as not failed to fall into the snare 

^^^e here ^ ^^^^ ^^ *^® adventurous theorist. We 

*^* has a d^^^ theory of the spleen. The spleen in 

*he digestin ^^^^^ office: it is ever found attached to 

^% ^onside "^^^ ^^ the intestinal canal ; and is reason- 

^^n to the f^ ^ afford occasional increase of circular 

*^*t quality^ ^^ach, and to supply blood to the liver of 

tJon of bile. ^ ^^^ appears necessary to a copious secre- 

*^»* Anat, p. 167, t Ibid. 



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238 KATURAL THEOLOGY. 

9. The s^ta of the brain probably pferenione 
part of the organ from pressing with too great 
a weight upon another part The processes of 
the dnra mater diride ihe cavity of the skulls like 
so many inner partition walls> and thereby confine 
each hemisphere Bxtd lobe of the brain to the 
chamber which is assigned to it> without its being 
liable to rest upon or intermix with the neigh- 
bouring parts. The great art and caution c^ 
packing is to prevent one thing hurting another. 
This> in the head, the chest and the abdomen, of 
an animal body, is, amongst other methods, pro- 
vided for 1^ membranous partitions and wrap- 
pings, which keep the parts separate. 

The above may serve as a short account of the 
manner in which the principal viscera are sus- 
tained in their places. But of the provisions for 
this purpose, by far, in my opinion, the most 
curious, and where also such a provision was most 
wanted, is in the giUs. It is pretty evident, that 
a long narrow tube (in man, about five times the 
length of the body) laid from side to side in folds 
upon one another, winding in oblique and dr- 
enitous directions, composed ako of a soft and 
j^elding substance, must, without some extraor- 
dinary precaution for its safety, be continually 
displaced by the various, sudden, and abrupt 
motions of the body which, eontaina it I should 



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NATURAL THEOLOGT. 239 

expect that, if not broisied or wounded by every 
faH, or leap> or twist, it wonld be entangled, or be 
xnTolyed with itsdf ; or, at the least, slipped and 
shaken out of the order in which it is disposed^ 
and which ord^ is necessary to be preserved for 
the carrying on ai the important fimctions which 
it has to execute in the animal economy. Let na 
see, therefore, how a danger so serious, and yet so 
natural to the length, narrowness, and tubular 
form of the part, is provided against. The expe- 
dient is admirable ; and it is this. The intestinal 
canid, throughout its wlu^ process, is knit to the 
edge of a broad fat membrane called the mesen* 
tery. It forms the margin of this mesentery, 
being stitched and fastened to it like the edging 
of a ruffle : being four times as long as the me- 
sentery itself, it is what a sempstress would caU 
^'puckered or gathered on" to it. This is the 
nature of the connexion of the gut with the me* 
sentery ; and being thus joined to, or rather made 
a part of, the mesentery, it is folded and wrapped 
inp together with it. Now the mesentery, having 
a considerable dimension in broadth, being in its 
substance withal both thick and suety, is capable 
of a dose and safe fcdkling, in comparison of what 
the intestinal tube would admit of, if it had re. 
mained loose. The mesentery likewise not only 
keeps the intestinal canal in its proper place and 



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-^^f— 1-1*^*- 



240 NATURAL THEOLOGY. 

position under all the turns and windings of its 
course, but sustains the numberless small vessels, 
the arteries, the veins, the lympheducts, and, above 
all, the lacteals, which lead from or to almost 
every point of its coats and cavity. This mem- 
brane, which appears to be the great support and 
security of the alimentary apparatus, is itself 
strongly tied to the first three vertebrae of the 
loins *. 

III. A third general property of animal forms 
is beauty, I do not mean relative beauty, or that 
of one individual above another of the same 
species, or of one species compared with another 
species; but I mean, generally, the provision 
which is made in the body of almost every animal 
to adapt its appearance to the perception of the 
animals with which it converses. In our own 
species, for example, only consider what the parts 
and materials are of which the fairest vbody is 
composed; and no further observation will be 
necessary to show how well these things are 
wrapped up, so as to form a mass which shall be 
capable of symmetry in its proportion, and of 
beauty in its aspect; how the bones are covered, the 
bowels concealed, the roughnesses of the muscle 
smoothed and softened ; and how over the whole 
is drawn an integument, which converts the dis- 
* KeiU's Anat. p. 45. 



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NATURAL THEOLOGY. 241 

gusting materials of a dissecting-room into an 
object of attraction U> the sight, or one upon 
wluch at rests at least with ease and satisfaction. 
Much of this effect is to be attributed to the in- 
tervenhonof the ceUular or adipose membrane, 
which hes mmiediately under the skin ; is a kind 
of hmngtoit; is moist, soft, slippery, and com- 
pressible; everywhere filling up the interstices of 
the muscles, and forming thereby their roundness 
and flowing U„e, as weU as the evenness and 
Pohsh of the whole surface. 

desl^ ^'^^f ;««f« to be a strong indication of 
design, and of a design studiously directed to this 
purpose. And it being once allowed that such a 

purpose existed with respect to any of the pro- 
duct ,f „^,^^^^ ^^ ^^^ ^^^^^ ^^^ ^ ^^^^ P^^ 

able degree of probabihty, other particulars to 
the same intention; such as the tints of flowers, 
the plumage of birds, the furs of beasts, the 
bnght scales of fishes, the painted wings of but- 
terflies and beetles, the rich colours and spotted 
lustre of many tribes of insects. 

.J:^ "^ P*^^ *^° °^ ^"^"^^l^ ornamental, 
and the properties by wWch they are so not sub- 
servient that we know of. to any other purpose, 
ine irides of most animals are very beautiful. 
Without conducing at all, by their beauty, to the 
perfection of vision ; and nature could in no part 



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242 NATtJRAL THEOLOGY. 

have employed her pencil to so much advantage^ 
because no part presents itself so conspicuously 
to the observer, or communicates so great an 
effect to the whole aspect* 

In plants^ especially in the flowers of plants^ 
the principle of beauty holds a still more consi- 
derable place in their composition ; is still more 
confessed than in animals. Why, for one instance 
out of a thousand, does the corolla of the tulip, 
when advanced to its size and maturity, change 
its colour? The purposes, so far as we can see, 
of vegetable nutrition might have been carried 
on as well by its continuing green. Or, if this 
could not be, consistently with the progress of 
vegetable life, why break into such a variety of 
coloiurs ? This is no proper effect of age, or of 
declension in the ascent of the sap ; for that, like 
the autumnal tints, would have produced one 
colour on one leaf, with marks of fading and 
withering. It seems a lame account to call it, as 
it has been called, a disease of the plant Is it 
not more probable that this property, which is 
independent, as it should seem, of the wants and 
utilities of the plant, was calculated for beauty, 
intended for display ? 

A ground, I know, of objection has been taken 
against the whole topic of argnment, namely, 
that, there is no such thing $s beauty at all; in 



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If ATUKAl TBEOLOGT. 243 

Other words, that whaterer is useful and famiEar 
comes of coinrse to be thought beautiful ; and that 
things appear to be so, only by their alliance with 
these qualities. Our. idea of beauty is capable 
of being in so great a degree modified by haW^ 
hy fashion, by the experience of advantage or 
pleasure, and hy associations arising oiit of that 
experience, that a question has been made, whe- 
ther it be not altogether generated by these 
causes, or would have any proper existence with- 
out them. It seems, however, a carrying of the 
conclusion too far, to deny the existence of the 
principle, viz., a native capacity of perceiving 
beauty, on account of an influence, or of varieties 
proceeding from that influence, to which it is 
subject, seeing that principles the most acknow- 
ledged are liabte to be affected in the same man^ 
ner. I shoidd rather argue thus : — The question 
respects objects of sight Now every other sense 
hath its £stinction of agreeable and disagreeable. 
Some tastes offend the psdate, others gratify it. 
In brutes and insects, this distinction is stronger 
and more regular than in man. Every horse, ox, 
sheep, swiner when at hberty to choose, and when 
in a natural state, that is, when not vitiated by 
habits fbreed upon i^ eats and rgeets the same 
plants. Many imeds which feed upon particular 
plants, will ni^er die than change theis appto^ 

m2 



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244 NATURAL THEOLOGY. 

priate leaf, All this looks like a determination 
in the sense itself to particular tastes. In like 
manner^ smells affect the nose with sensations 
pleasurable or disgusting. Some sounds^ or 
compositions of sound, delight the ear : others 
torture it. Habit can do much in all these cases 
(and it is well for us that it can ; for it is this 
power which reconciles us to many necessities) ; 
but has the distinction, in the mean time, of 
agreeable and disagreeable, no foundation in the 
sense itself? What is true of the other senses is 
most probably true of the eye (the analogy is 
irresistible), viz., that there belongs to it an ori- 
ginal constitution, fitted to receive pleasure from 
6ome impressions, and pain from others. 

I do not however know, that the argument 
which alleges beauty as a final cause rests upon 
this concession. We possess a sense of beauty, 
however we come by it. It in fact exists. Things 
are not indifferent to this sense; all objects do 
not suit it ; many, which we see, are agreeable to 
it : many others disagreeable. It is certainly not 
the effect of habit upon the particular object, be- 
cause the most agreeable objects are often the 
most rare ; many which are very common, con- 
tinue to be offensive. If they be made support- 
able by habit, it is all which habit can do ; they 
aiever become agreeable. If this sense, therefore. 



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NATURAL THEOLOGY. 24S 

be acquired, it is a result ; the produce of nume- 
rous and complicated actions of external objects 
upon the senses, and of the mind upon its sensa- 
tions. With this result, there must be a certain 
congruity to enable any particular object to please; 
and that congruity, we contend, is consulted in 
the aspect which is given to animal and vegetable 
bodies. 

IV. The skin and covering of animals is that 
upon which their appearance chiefly depends; and 
it is that part which, perhaps, in all animals, is 
most decorated, and most free from impurities. But 
were beauty, or agreeableness of aspect, entirely 
out of the question, there is another purpose 
answered by this integument, and by the colloca* 
tion of the parts pf the body beneath it, which is 
^f stiU greater importance ; and that purpose is 
concealment. Were it possible to view through 
the skin the mechanism of our bodies, the sight 
would frighten us out of our wits. " Durst we 
make a single movement," asks a lively French 
writer, *' or stir a step from the place we were in, 
if we saw our blood circulating, the tendons pull- 
ing, the lungs blowing, the humours filtrating, 
and all the incomprehensible €issemblage of fibres, 
tubes, pumps, valves, currents, pivots, which sus- 
tain an existence at once so frail and so pre^ 
sumptuous?" 



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246 NATURAL THE<tt.OGY, 

V. Of animal bodies, considered as masses, 
there is another property, more curious than it is 
generally thought to be ; which w the faculty of 
standing : and it is more remarkable in two- 
legged animals than in quadrupeds, and, most of 
an, as being the tallest, and resting upon the 
smallest base, in man. There is more, I think, in 
the matter than we are aware of. The statue of a 
man, placed loosely upon a pedestal, would not 
be secure of standing half an hour. You are 
obliged to fix its feet to the block by bolts and 
solder; or the first shake, the first gust of wind^ 
is sure to throw it down. Yet this statue shall 
express aU the mechanical proportions of a Hving 
model. It is not then^ore the mere figure, or 
merely placing the centre of grarity within the 
base, that is suffici^it. Either the law of gravi- 
tation is suspended in fi&TOur of living substances, 
or something more is done fi>r them, in order to 
enaMe them to uphold their posture. There is 
no reason whatever to doubt, but that their parts 
descend by gravitation in the ^ame manner as 
diose of dead matter. The gift tbere£)re appears 
to me to consist in a &cultj of perpetually shifting 
the centre of gravity, by a set of obsciu'e, indeed, 
but oi quick-balancing actions, so as to keep the 
line of direction, which is a line drawn firom that 
centre to the ground, within its prescribed Umit9« 



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NATURAL THEOLOGY. 24^ 

Of these actions it may biD observed^ first, that 
they in part constitute what we call strength. 
The dead body drops down. The mere adjust- 
ment therefore of weight and pressure^ which may 
be the same the moment after death as the mo- 
ment before, does not support the column. In 
cases also of extreme weakness, the patient cannot 
stand upright. Secondly, that these actions are 
only in a small degree voluntary. A man is sel- 
dom conscious of his voluntary powers in teeping 
himself upon his legs. A child learning to waUc 
is the greatest posture-master in th6 world : but 
art, if it may be so called, sinks into habit; and 
he is soon able to poise himself in a great variety 
of attitudes, without being sensible either of cau* 
tion or effort. But still there must be an aptitude 
of parts, upon which habit can thus attach; a pre» 
vious capacity of motions which the animal is thus 
taught tp exercise : and the facility with which 
this exercise is acqudred forms one object of our 
admiration. What parts are principally employed, 
or in what manner each contributes to its office, 
is, as hath already been confessed, difficult to ex- 
plain. Perhaps the obscure motion of the bones 
of ihe feet may have their share in this effect. 
They are put in action by every slip or vacillation 
of the body, and seem to assist in restoring its 
balance. Certain it is, that this circumstance in 



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.248 NATURAL THEOLOGY. 

the structure of the foot, viz.> its being composed 
of many small bones^ applied to and articulating 
Irith one another by diversely-shaped surfaces, 
instead of being made of one piece, like the last 
of a shoe, is very remarkable. 




I suppose also that it would be difficult to stand 
firmly upon stilts or wooden legs, though their 
base exactly imitated the figure and dimensions 
of the sole of the foot. The alternation of the 
joints, the knee-joint bending backward, the hip- 
joint forward ; the flexibiUty, in every direction, 
of the spine, especially in the loins and neck, 
appear to be of great moment in preserving the 
equilibrium of the body. With respect to this 
last circumstance, it is observable, that the ver- 
tebrae are so confined by ligaments as to allow no 
more slipping upon their bases, than what is just 
sufficient to break the shock which any violent 
motion may occasion to the body. A certain 
degree also of tension of the sinews appears to be 
essential to an erect posture ; for it is by the loss 
of this that the dead or paralytic body drops 



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NATURAL THEOLOGt. 249 

down. The whole is a wonderful result of com- 
bined powers, and of very complicated operations, 
windeed, that standing is not so simple a business 
as we imagine it to be, is evident from the strange 
gesticulations of a drunken man, who lias lost the 
government of the centre of gravity **. 

*• All this is admirably well put by our author. Yet 
when he says "the gift consists in the faculty of perpe- 
tually shifting the centre of gravity, hy a set of ohscure, 
indeed, but of quick halancing actions," he states a fact^ 
hut omits the most surprising circumstance of all. No 
douht such efforts are made; but what directs them? 
If a man should balance a staff, resting it on the point ^ 
of the finger, he shifts the hnger continually, in doing 
which he is directed hy the eye — ^he sees the staflf in- 
cHning. How does a man judge of the inchnation bf *^ 
his hody in the very first degree of deviation from the 
perpendicular? He does not see himself, nor is he 
directed by the objects around him, since a blind man 
will stand as securely as one who sees. The fact is, that 
he has a knowledge of muscular action — a sensibiUty 
to the finest adjustment of the muscles, hy which he di- 
rects their eflforts. This sense is of all the most marvel- 
lous : a sensihility to an internal motion, more minute 
and curious than are the sensibiUties to external im- 
pression ; and which, as may he easily proved, minis- 
ters to a variety of properties in the living body, and 
especially to the organs of sense themselves. 

m3 



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j250 IfATURAL THSOLOQT* 

We have said that this property is the mo«t 
worthy of obeeryatioii in the human body ; Iwt ft 
bird, resting upon its perch> or hopping upon ft 
4^ay^ affi>rds no mean specimen of die same 
£iculty. A ehicken runs off as soon as it is 
hatched from the egg; yet a diicken^ considered 
geometrically, and with relation to its centre of 
gravity, its line of direction, and its equihbrium, 
is a very irregular solid. Is this gift, therefore, 
or instruction ? May it not be said to be with 
great attention that nature hath balanced the 
"body upon its pivots ? 

X observe also in the same bird a piece of use- 
ful mechanism of this kind. In the trussing of a 
fowl, upon bending the legs and thighs up to- 
wards the body^ the cook finds that the claws 
dose of their own accord. Now let it be remem- 
bered, that this is the position of the limbs in 
which the bird rests upon its perch. And in this 
position it sleeps in safety ; for the claws do their 
office in keeping hold of the support — ^not by any 
exertion of voluntary power, which sleep might 
suspend, but by the traction of the tendons in 
consequence of the attitude which the legs and 
thighs take by the bird sitting down, and to which 
the mere weight of the body gives the force that 
is necessary. 

VI. Regarding the human body as a mass; 



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NATURAL THEOLOOT. 251 

regarding the general conformations which ob- 
tain in it; regarding also particular parts in 
respect to those conformations; we shall be led 
to observe what I call "interrupted analogies.'* 
The following are examples of what I mean hj 
these terms ; and I do not know how such critical 
deviations can, by any possible hypothesis, be ac- 
counted for without design: — 

1. All the bones of the body are covered with 
a periosteum, except the teeth, where it ceases; 
and an enamel of ivory, which saws and files will 
hardly touch, comes into its place. No one can 
doubt of the use and propriety of this difference ; 
of the "analogy" being thus "interrupted;" of 
the rule, which belongs to the conformation of 
the bones, stopping wher€ it does stop ; for, had 
so exquisitely sensible a membrane as the perios- 
teum invested the teeth, as it invests every other 
bone of the body, their action, necessary exposure, 
and irritation, would have subjected the animal 
to continual pain. General as it is, it was not 
the^sort of integument which suited the teeth; 
what they stood in need of was a strong, hard^ 
insensible, defensive coat; and exactly such a 
covering is given to them, in the ivory enamel 
which adheres to their surface.*' 

*'^ See the dissertation on the teeth, in the Appendix. 



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252 NATURAL THEOLOGY. 

2. The scarf-sldn, which clothes all the rest of 
the body, gives way, at the extremities of the 
toes and fingers, to naUs. A man has only to 
look at his band, to observe with what nicety and 
precision that covering, which extends over every 
other part, is here superseded by a different sub^ 
stance and a different texture. Now, if either 
the rule had been necessary, or the deviation 
firom it accidental, this effect would not be seen. 
When I speak of the rule being necessary, I 
mean the formation of the skin upon the surface 
being produced by a set of causes constituted 
without design, and acting, as all ignorant causes 
must act, by a general operation. Were this the 
case, no account could be given of the operation 
being suspended at the fingers' ends, or on the 
back part of the fingers, and not on the fore part. 
On the other hand : if the deviation were acci- 
dental, an error, an anomalism — were it any thing 
else than settled by intention — we should meet 
with nails upon other parts of the body: they 
would be scattered over the surface, like warts or 
pimples.^ 

^ The human nail is calculated to support the cushion 
of the extremity of the finger, and is important to us in 
grasping or holding any thing ; but more so still in sus- 
taining that cushion as the chief organ of touch. There 
are other parts of the body which have exquisite sensi* 



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•KATURAL THEOLOOt, 253 

3. All the great cavities of the body are en- 
closed by membranes, except the skulL Why 
should not the brain be content with the same 
covering as that which serves for the other prin- 
cipal organs of the body ? The heart, the lungs, 
the liver, the stomach, the bowels, have all soft 
• integuments, and nothing else. The muscular 
coats are all soft and membranous. I can see a 
reason for this distinction in the final cause, but 
•in no other. The importance of the brain to life 
(which experience proves to be immediate), and 
-the extreme tenderness of its substance, make a 
solid case more necessary for it, than for any 
other part ; and such a case the hardness of the 
skull supplies.** When the smallest portion of 

bility, yet they are not provided so as to give us that 
information of the condition of matter which we have 
through the finger, and in a lesser degree through the 
whole inner surface of the hand. We easily feel, for 
example, the pulsation of the artery at the wrist, through 
the combination of the sensibility of the nerve of touch 
with the elastic cushion of the finger. The best proof 
of the use of the elastic cushion is this : — Although the 
tip of the tongue feels so exquisitely that the presence 
of a hair of wool troubles us, yet if we apply it to the 
pulse we shall not be sensible of the beat. 

*• There is a note upon the form of the skull in the 
Appendix, which may interest the reader* 



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254 NATURAL THBOLOaT. 

tills natural casket is lost> how carefiilly> yet bow 
imperfectly^ is it replaced by a plate of metal ! 
If an anatomist should say^ that this bony pro- 
tection is not confined to the brain^ but is ex- 
tended along the course of the spine, I ai»wer> 
that he adds strength to the argument. If he 
remark, that the diest also is fortified by bone«> 
I reply, that I should have alleged this instance 
myself, if the ribs had not appeared subservient 
to the purpose of motion as well as of d^ence. 
What distinguishes the skuU from ev^y other 
cavity is, that the bony covering completely sur- 
rounds its contents, and is calculated, not for 
motion, but solely for defence. Those hcdlows, 
likewise, and inequalities which we observe in the 
inside of the skull, and which exactly fit the folds 
of the brain, answer the important design of 
keeping the substance of the brain steady, and of 
guarding it against concussions. 



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NATURAL THEOIXKJT. ^5 

CHAPTER XIL 

COMPARATIVE ANATOMY. 

Whenever we find a general plan pursued, yet 
with such variations in it as are, in each ease> 
required by the particular exigency of the subject 
to which it is applied, we possess, in such a plan 
and jsueh adaptation, the strongest evidence that 
can be afforded of intdhgence and d^ign : an 
evidence which the most completely excludes every 
other hypothesis. If the general plan proceeded 
from any fixed necessity in the nature of things, 
how could it accommodate itself to the various 
wants and uses which it had to serve under dif- 
ferent circumstances, and on different occasions? 
Arkwrigkta mill was invented for the spinning of 
cotton. We see it employed for the spinning of 
wool, flax, and hemp, with such modifications of 
the original principle, such variety in the same 
plan, as the texture of those different materials 
rendered necessary. Of the machine's being put 
together with design, if it were possible to doubt 
whilst we saw it only under one mode, and in one 
form; when we came to observe it iii its different 
applications, with such dianges of structure, such 



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256 NATURAL THEOLOOT, 

additions and supplements, as the special and 
particular use in each case demanded, we could 
not refiise any longer our assent to the proposi- 
tion — " that intelligence, properly and strictly so 
called (including, under that name, foresight, con* 
sideration, reference to utility), had been em- 
ployed, as well in the primitive plan, as in the 
several changes and accommodations which it is 
made to imdergo." 

Very much of this reasoning is applicable to 
what has been called Comparatwe Anatomy, In 
their general economy, in the outlines of the plan, 
in the construction as well as offices of their prin- 
cipal parts, there exists between all large terres- 
trial animals a close resemblance. In all, life is 
sustained, and the body nourished, by nearly the 
same apparatus. The heart, the lungs, the sto- 
mach, the liver, the kidneys, are much alike in 
all. The same fluid (for no distinction of blood 
has been observed) circulates through their ves- 
sels, and nearly in the same order. The same 
cause, therefbre, whatever that cause was, hais 
been concerned in the origin, has governed the 
production, of these different animal forms. 

When we pass on to smaller animals, or to th^ 
inhabitants of a different element, the resemblance 
becomes more distant and more obscure; but still 
the plan accompanies us. 



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NATURAL THEOLOGY. 257 

And« what we can never enough commend^ and 
which it is our business at present to exemplify, 
the plan is attended, through all its varieties and 
deflections, by subserviences to special occasions 
and utilities. 

I. The covering of difierent animals (though 
whether I am correct in classing this under theiir 
-anatomy, I do not know) is the first thing which 
"presents itself to our observation; and is, in 
truth, both for its variety and its suitableness to 
4heir several natures, as much to be admired as 
•any part of their structure. We have bristles, 
hair, wool, ftirs, feathers, quills, prickles, scales ; 
yet in this diversity both of material and form, 
we cannot change one animaFs coat for another, 
without evidently changing it for the worse; — 
taking care, however, to remark, that these co- 
verings are, in many cases, arm.our as well ad 
clothing; intended for protection as well as 
warmth. 

The human animal is the only one which is 
naked, and the only one which can clothe itself. 
This is one of the properties which renders him 
an animal of all climates, and of all seasons. He 
can adapt the warmth or lightness of his covering 
to the temperature of his habitation. Had he 
been born vnth. a fleece upon his back, although 
he might have been comforted by its warmth in 



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258 NATURAL THKOLOQT. 

high httitudes, it would have oppressed him by 
its weight and heat> as the species spread towards 
the equator. 

What art, however^ does for men, nature has, 
in many instances, done for those animals which 
are incapable of art. Their clothing, of its own 
accord, changes with their necessities. This is 
particularly the case with that large tribe of qua- 
drupeds which are covered with furt. Every 
dealer in hare-skins and rabbit-skins knows how 
mudi the for is thickened by the approach of 
winter. It seems to be a part of the same con- 
stitution and the same design, that wool^ in hot 
countries^ degenerates, as it is x^alled, but in truth 
(most happily for the animal's ease) passes into 
hair; whilst, on the contrary, that hair, in the 
dogs of the polar regions, is turned into wool, or 
something very like it. To which may be re* 
lerred, what naturalists have remarked, that bears^ 
wolves, foxes, hares, which do not take the water, 
have the fur much thicker on the back than the 
belly; whereas in the beaver it is the thickest 
upon the belly; as are the feathers in water-fowl. 
We know the final cause of all this, and we know 
no other. 

The covering of birds cannot escape the most 
vulgar observation : its lightness, its smoothness, 
its warmth — ^the disposition of the feathers all 



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JJATURAL THEOLOGY. 259 

iiK^lined backward, the down alKmt their stem, the 
overlapping of their tips, their <^erent configura^ 
tion in diiOferent part8» not to mention the variety 
of their colours, constitute a vestment for th^ 
body, so beautiful, and so appropriate to the life 
which the animal is to lead, as that, I think, we 
should have had no conception of any thing 
iwjually perfect, if we had never seen it, or can 
now imagine any thing more so. Let us sup* 
Jwse (what is possible only in supposition) a per* 
son who had never seen a bird to be presented 
with a plucked pheasant, and bid to set his wits 
to work how to contrive for it a covering which 
shall unite the qualities of warmth^ levity, and 
least resistance to the air, and the highest degree 
of each ; giving it also as much of beauiy and 
ornament as he could afford. He is the person 
to behold the work of the Deity, in this part of 
his creation, with the sentiments which are duo 
to it 

. The commendation which the general aspect erf 
the feathered world seldom fails of exciting will 
be increased by fiirther examination. It is one of 
those cases in which the philosopher has more to 
admire than the common observer. "EYery feather 
is a mechanical wonder. If we look at the quill, 
we find properties not easily brought together, 
strength and Kghtness. I know few things more 



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260 NATURAL THEOLOGY. 

remarkable than the strength and lightness of the 
Tery pen with which I am writing. If we cast 
our eye to the upper part of the stem^ we see a 
material^ made for the purpose, used in no other 
class of animals^ and in no other part of birds, 
tough, light, pliant, elastic. The pith also which 
feeds the feathers is, amongst animal substances, 
»iii generis — ^neither bone, flesh, membrane, nor 
tendon*. 

But the artificial part of a feather is the beard, 
OT, as it is sometimes, I believe, called, the vane* 
By the beards are meant what are fastened on 
each side of the stem, and what constitute the 
breadth of the feather, what we usually strip off 
from one side or both when we make a pen. The 
separate pieces, or laminae, of which the beard is 
composed, are called threads, sometimes filaments 
or rays. Now, the first thing which an attentive 
observer will remark is, how much stronger the 
beard of the feather shows itself to be when 
pressed in a direction perpendicular to its plane, 
than when rubbed, either up or down, in the line 
of the stem ; and he will soon discover the struc- 
ture which occasions this difference, viz., that the 

^ The quill part of a feather it composed of circular and longi- 
tudinal fibres. In making a pen, you must scrape oS'the coat of 
circular fibres, or the quill will split in a ragged, jagged manner, 
taking what boys call ca/V teeth. 



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NATURAL THEOLOGY^ 261 

laminae whereof these beards are composed are 
flat, and placed with their flat sides towards each 
other, by which means, whilst they easily bend for 
the approaching of each other, as any one may 
perceive by drawing his finger ever so lightly up-* 
wards, they are much harder to bend Out of theit 
plane, which is the direction in which they have to 
encounter the impulse and pressure of the air, 
and in which their strength is wanted and put to 
the trial. 

This is one particularity in the structure of a 
feather : a second is still more extraordinary. 
Whoever examines a feather cannot help taking 
tiotice, that the threads or laminae of which wo 
kave been speaking, in their natural state, unite — . 
that their union is something more than the mere 
apposition of loose surfaces — that they are not 
parted asunder without some degree of force — - 
that, nevertheless, there is no glutinous cohesion 
between them — that, therefore, by some mechani- 
cal means or other, they catch or clasp among 
themselves, thereby giving to the beard or vane 
its closeness and compactness of texture. Nor ia^ 
this all : when two laminae which have been sepa- 
^^ted by accident or force are brought together 
Sigain, they immediately reclasp ; the connexion* 
whatever it was, is perfectly recovered, and tho 
beard of the feather becomes as smooth and firm. 



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262 NATURAL THEOLOGY* 

as if notliiiig had happened to it Draw your 
finger down the feather, which is against the 
grain, and you break, probably, the junction of 
some of the contiguous threads ; draw your finger 
up the feather, and you restore all things to thar 
fi[>nner state. This is no common contrivance; 
imd nowfor the mechanism by which it is effected. 
The threads or laminae above mentioned are inter^ 
laced with one another; and the interlacing is 
performed by means of a vast number of fibres 
or teeth, which the laminae shoot forth on each side, 
and which hook and grapple together* A friend 
of mine counted fifty of these fibres in one-twen- 
tieth of an inch. These fibres are crooked, but 
curved after a diSS^ent manner; for those which 
proceed firom the thread on the side towards the 
extremity of the feather are longer, more flexibly 
and bent downward; whereas those which pro- 
ceed firom the mde towards the beginning or quill 
end of the feather are shorter, firmer, and turn 
upwards. The process, then, which takes place is 
as follows : when two laminae are pressed toge- 
ther, so that these long fibres are fiovced &r 
enough over the short onesy thdr crooked parts 
fill into the cavity made by the crooked parts of 
the others, just as the latch that is fastened to ft 
door enters into the cavity of the catch fixed to 
the door-post, and there hooking itself, fastens the 



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NATURAL THEOLOGY, 263 

door; for it is properly in this manner that one 
thread of a feather is fastened to the other. 

This admirable structure of the feather, which 
it is easy to see with the nncroscope, succeeds 
perfectly for the use to which nature has designed 
it, which use was, not only that the laminae might 
be united, but that, when one thread or lamina 
has been separated from another by some exter- 
nal violence, it might be reclasped with sufficient 
&ci]ity and expedition*. 

In the ostrich, this apparatus of crotchets and 
fibres, of hooks and teeth, is wanting; and we see 
the consequence of the want. The filaments 
hang loose and separate from one another, form- 
ing only a kind of down, which constitution of 
the feathers, however it may fit them for the 
flowing honours of a lady's head-dress, may be 
reckoned an imperfection in the bird, inasmuch 
as wings composed of these feathers, although 
they may greatly assist it in running, do not 
serve for flight. 

But> under the present division of our subject, 
our business with feathers is as they are the 
covering of the bird. And herein a singular cir- 
cumstance occurs. In the small order of birds 

^ The above account is talcen from Memoirs for a Natural His* 
tory of Animals, by tlie Royal Academy of Paris, published in 
1701, p. 219. 



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264 NATURAL THEOLOGY, 

which winter with us, firom a snipe downwards^ 
let the external colour of the feathers be what it 
will, their Creator has universally given them a 
bed of black down next their bodies. Black> 
we know, is the wannest colour ; and the purpose 
here is^ to keep in the heat arising firom the heart 
and circulation of the blood • It is fiirther like^ 

^ When we attempt to apply the lights of experi- 
mental philosophy to this subject, the inquiry is not a 
little embarrassing. A loose woolly texture, or down, 
as it implies the presence of air in its interstices, air 
being a bad conductor of heat, is therefore a warm 
covering : it prevents the expenditure of animal heat. 
When we consider the colour of the coverings of birds j 
we must take new elements into our process of rea- 
soning — we must reflect on the effects of the conduction 
and radiation of heat. The conduction is the convey- 
ance of heat ; and the radiation is the parting with it 
into the atmosphere or into space. We have already 
explained why the interior covering of the arctic bird 
should be loose : as to the colour, its effect must result 
from radiation. It appears (to use the vulgar lan- 
guage) that the influence of cold both on quadrupeds 
and birds is to increase their woolly or downy covering*, 
and, in many instances, to change the exterior colour td 
white : in other und more correct words, a provision is 
made for changing their clothing so as to suit their 
altered circumstances. This change of colour corrcr 



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NATURAL THEOLOGY. 265 

wise remarkable, that this is not found in larger 
birds ; for which there is also a reason. Small 
birds are much more exposed to the cold than 
large ones, forasmuch as they present, in propor- 
tion to their bulk, a much larger surface to the 
air. If a turkey were divided into a number of 
wrens (supposing the shape of the turkey and the 
wren to be similar), the surface of all the wrens 
would exceed the surface of the turkey in the 
proportion of the length, breadth (or of any ho- 
mologous line) of a turkey to that of a wren, 
which would be, perhaps, a proportion of ten to 
one. It was necessary, therefore, that small birds 
should be more warmly clad than large ones ; and 
tliis seems to be the expedient by which that exi- 
gency is provided for. 

II. In comparing different animals, I know no 
part of their structure which exhibits greater va- 
riety, or, in that variety, a nicer accommodation to 
^their respective conveniency than that which is 
seen in the different formations of their mouths. 
Whether the purpose be the reception of aliment 
merely, or the catching of prey, the picking up of 

spends with philosophical experiments — a white surface 
absorbing the least, and radiating the least, it should 
therefore tend to confine the vital heat within the ani- 
mal, and carry it off slowly to the atmosphere. 

N 



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266 NATURAL THEOLOGY. 

seeds, the cropping of herbage, the extraction of 
juices, the suction of liquids, the lireaking and 
grinding of food, the taste of that food, together 
with the respiration of air, and, in conjunction 
with it, the utterance of sound; these various 
offices are assigned to this one part, and, in dif- 
ferent species, provided for as they are wanted by 
its different constitution. In the human species, 
forasmuch as there are hands to convey the food 
to the mouth, the mouth is fiat, and by reason of 
its flatness, fitted only for reception; whereas the 
projecting jaws, the wide rictus, the pointed teeth 
of the dog and his affinities, enable them to apply 
their mouths to snatch and seize the objects of 
their pursuit. The fiiU Kps, the rough tongue, 
the corrugated cartilaginous palate, the broad 
cutting teeth of the ox, the deer, the horse, and 
the sheep qualify this tribe for browsing upon 
their pasture; either gathering large mouthfuls 
at once, where the grass is long, which is the case 
with the ox in particular, or biting close where it 
is short, which the horse and the sheep are able 
to do in a degree that one could hardly expect 
The retired under-jaw of a smne works in the 
ground, after the protruding snout, like a prong 
or plough-share, has made its way to the roots 
upon which it feeds. A conformation so happy 
was not the gift of chance. 



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NATURAL THEOLOGY. 



267 




In birds, this organ assumes a new character; 
new both in substance and in forrn^ but in both 
wonderfully adapted to the wants and uses of a 
distinct mode of existence. We have no longer 
the fleshy lips, the teeth of enamelled bone; but 
we have, in the place of these two parts, and to 
perform the office of both, a hard substance (of 
the same nature with that which composes the 
nails, claws, and hoofs of quadrupeds), cut out 
into proper shapes, and mechanically suited to 
the actions which are wanted. The sharp edge 
and tempered point of the sparrow's bill picks 
almost every kind of seed from its concealment in 
the plant, and not only so, but huUs the grain, 
breaks and shatters the coats of the seed, in order 
to get at the kernel. The hooked beak of the 

n2 



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268 NATURAL THEOLOGY. 

hawk tribe separates the flesh from the bones of 
the animals which it feeds upon, almost with the 
cleanness and precision of a dissector's knife. 
The butcher-bird transfixes its prey upon the 
spike of a thorn whilst it picks its bones. In 
some birds of this class we have the cross bill, i. e., 
both the upper and lower bill hooked, and their 
tips crossing. The spoon bill enables the goose 
to graze, to collect its food from the bottom of 
pools, or to seek it amidst the soft or liquid sub- 
stances with which it is mixed. The long tapering 
bill of the snipe and woodcock penetrates still 
deeper into moist earth, which is the bed in which 
the food of that species is lodged. This is ex- 
actly the instrument which the animal wanted. 
It did not want strength in its bill, which was 
inconsistent with the slender form of the animal's 
neck, as well as unnecessary for the kind of ali- 
ment upon which it subsists; but it wanted length 
to reach its object". 

*^ With the instrument, as we have before hinted, we 
should expect a particular instinctive action, and a cor- 
responding muscular power. As an animal with horns 
has a powerful neck, so has the neck of the heron, which 
is introduced here, an extraordinary muscular power, 
without which, indeed, the long and sharp bill would be 
of little use. When the dog approaches the wounded 



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NATURAL THEOLOGY. 269 

But the species of bill which belongs to the 
birds that live by suction deserves to.be described 

heron, the bird throws itself upon its back, and, retract- 
ing its long neck, suddenly darts it out with a force 
which strikes the bill deep into the dog. If you hold 




your hat towards the bird, the bill will be struck quite 
through it. In contending with the hawk, when the 
latter is spitted, it is not by the rapid descent of the 
hawk, but by the force with which the heron drives its 
bill. 

The strength of the bill of the parrot, and that of all 
birds which break the stones of fruit, or nuts, or hard 
seeds, is in another direction : the bill is hooked, yet is 
differently formed from that of the carnivorous bird. 
The intention is, in the first place, that the point 
shall play vertically, which, with the strengthening of 
successive layers near the point, enables it to break 
hard materials ; and secondly, that by this form the nut 
or seed may be brought nearer the joining or articulation 
of the jaw, which gives the same advantage that we 



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270 NATURAL THEOLOGY. 

in its rektion to that office* Tliey are "whzt na- 
taralists call senmted or dentated bilk ; Ae inside 
of them, towards the edge, being thickly set with 
parallel or concentric rows of short, strong, sharp- 
pointed prickles. These, though they should be 
called teeth, are not for the purpose of mastica- 
tion, like the teeth of quadrupeds ; nor yet, as in 
fish, for the seizing and retaining of their prey; 
but for a quite different use. They form a filtre. 
The duck by means of them discusses the mud; 

have when we put a nut nearer the joint of the nut- 
cracker, that is, nearer the fulcrum. 

One disadvantage of this form and shortness of the 
bill would be, that the mandibles could not open wide 
enough to take in a large seed ; but it is provided that the 
upper mandible shall move upon the skull as well as the 
lower one, a subject which has not escaped our author^s 
attention. 

The form of the bill of the cross-bill, which he men- 
tions, looks like an imperfection, but is attended with 
real advantages. It is not for crushing, but rather for 
splitting up a seed into halves, and tearing the cones of 
the fir-tree. 

One of the most curious provisions is in the bill of the 
sea-crow. The mandibles are compressed into the form 
of simple laminee, and the lower mandible projects be- 
yond the upper one ; so that, as he skims along the water, 
he dips his bill and lifts his food by the most appropriate 
instrument. 



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NATURAL THEOLOGY. 271 

examming with great accuracy the puddle, the 
l»rake> every mixture which i& likdy to contain her 
food. The operation is thus carried on: — The 




liquid or semi-liquid substances in which the ani- 
mal has plunged her bUl, she draws> by the action 
of her lungs, through the narrow interstices which 
lie between these teeth, catching, as the stream 
passes across her beak^ whatever it may happ^i 
to bring along vriith it that proves agreeable to 
her choice, and easily dismissing all the rest. 
Now, suppose the purpose to have been, out of a 
mass of confiised and heterogeneous substanceiB, 
to separate for the use of the animal, or rather to 
enable the animal to separate for its own, those 
few particles which suited its taste and digestion, 
what more artificial or more commodious instru- 
ment of selection could have been given to it than 



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272 NATURAL THEOLOGY. 

this natural filtrc ? It has been observed also (what 
must enable the bird to choose and distinguish 
with greater acuteness, as vrcU, probably, as what 
greatly increases its luxury) that the bills of this 
species are furnished with large nerves, that they 
arc covered with a skin, and that the nerves run 
down to the very extremity. In the curlew, wood- 
cock, and snipe, there are three pairs of nerves, 
equal almost to the optic nerve in thickness, which 
pass first along the roof of the mouth, and then 
along the upper chap down to the point of the 
bill, long as the bill is". 

But to return to the train of our observations. 
The similitude between the biUs of birds and the 
mouths of quadrupeds is exactly such as, for the 
sake of the argument, might be wished for. It 
is near enough to show the continuation of the 
same plan : it is remote enough to exclude the 
supposition of the difference being produced by 
action or use. A more prominent contour, or a 
wider gap, might be resolved into the effect of 
continued efforts, on the part of the species, to 
thrust out the mouth or open it to the stretch. 
But by what course of action, or exercise, or en- 

*• These are branches of the fifth nerve of the head, 
which alone, of all the nine nerves of the brain, bestows 
sensibility on the organ of touch. 



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NATURAL THEOLOGY. 273 

deavour, shall we get rid of the lips, the gums, the 
teeth, and acquire in the place of them pincers of 
horn? By what habit shall we so completely 
change, not only the shape of the part, but the 
substance of which it is composed ? The truth is, 
if we had seen no other than the mouths of qua- 
drupeds, we should have thought no other could 
have been formed : little could we have supposed 
that all the purposes of a mouth furnished with 
lips and armed with teeth could be answered by 
an instrument which had none of these — could be 
supplied, and that with many additional advan- 
tages, by the hardness, and sharpness, and figure 
of the bills of birds. Everything about the ani- 
mal mouth is mechanical. The teeth of fish have- 
their points turned backward, like the teeth of a 
wool or cotton card. The teeth of lobsters work 
one against another, Hke the sides of a pair of 
shears. In many insects, the mouth is converted 
into a pump or sucker, fitted at the end sometimes 
with a wimble, sometimes with a forceps; by 
which double provision, viz., of the tube and the 
penetrating form of the point, the insect first 
bores through the integuments of its prey, and 
then extracts the juices. And what is most ex- 
traordinary of all, one sort of mouth, as the occa- 
sion requires, shall be changed into another sort. 
The caterpillar could not live without teeth; in 

n3 



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274 KATURAL THBOLOOT. 

amreral vpedes tiie batterfly formed fipom it oodtd 
mot use diem. The old teetli, tberefiore, are ca0l 
off witli tlie exuTue of ihe grub ; a new and totalfy 
different apparatus assumes tiieir place in tiie ij. 
Amid these novelties of £ann^ we sometimes fi)rget 
that it is an the while the animal's tnauik; that> 
whether it be lip8> or te^h, or bill, or beak, or 
shears, or ]mmp, it is the same part diversified; 
and it is also remarkable, that, under all the va- 
rieties of configuration with which we axe ac- 
quainted, and which are very great, the organs of 
tai^e and smelling Mre situated near each other. 

III. To the mouth a4]yosBS the guUet : in this 
part also, comparative anatomy discovers a differ- 
ence of structure adapted to the diffiereBt neces- 
sities of the animal. In barutes, because the pos- 
ture of thdr neck conduces little to the passage of 
the aliment, the fibres of the gnlkt which act in 
this business run in two dose spiral Hues, crossing 
each other : in men these fibres run only a little 
obliquely from the upper end of the oesophagus to 
the stomadi, into whidi, hj a gentle contractioi!!, 
they easily transmit the descending moraeli — diat 
is to say, for tke more laborious degfaititicHt of 
animals which thrust thdr food t^i instead of 
down, and also through a longer passage, a pfo- 
portionaUy more powerful appanrtufi of musides 
is provided — ^more powerful, not merely by Ae 



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NATURAL THEOLOGY. 275 

E^engtk of the fibres, whidi wagjai he aitr&aied 
to the g:i!eater ex^cise of their force^ but in their 
eoUocalion^ whi^ is a deteniuikate circiunstance^ 
imd must hare been oiiginaL 

IV. Ihe gull^ leads to the imie^tmeg : here, 
Hkewis^ as before^ c(»a»paring quadrupeds with 
man, under a general similitude we meet with ap- 
propr iate differences* The vakmlds emmwentes, or, 
as they are by some called, the semi-lunar valves, 
found in tlie human intestine are wanlmg in that 
of brutes. These are wrinkles or plates of the 
iB&ermost coat of the guts> the effect of which is 
to retard the progress of the food through tl^ 
alimentary canaL It is easy to understand how 
much more necessary such a provision may be to 
the body of an anim^ of an erect posture, and in 
which, consequently, the weight of the food is 
added to the action o£ the intestine, than in that 
of a quadn^>ed, in which the course of the food, 
£rom its entrance to its exit^ is nearly horizontal ; 
but it is impossible to assign any cause,^ except the 
fiaal cause, for this distinction actually takmg 
place. So far as depends upcm the action of the 
part, this structure was more to be &q>ected in a 
quadruped than in a man. In truth, it must in 
both have been formed, not by action, but in di- 
rect opposition to action and to pressure; but the 
opposition which would arise from pressure is 



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276 NATURAL THEOLOGY. 

greater in the upright trunk than in any other. 
That theory^ therefore, is pointedly contradicted 
by the example before us. The structure is found 
where its generation, according to the method by 
which the theorist would have it generated, 
is the most difficult; but, observe, it is found 
where its effect is most usefid. 

The different length of the intestines in carni- 
vorous and herbivorous animals has been noticed 
on a former occasion. The shortest, I believe, is 
that of some birds of prey, in which the intestinal 
canal is little more than a straight passage from 
the mouth to the vent. The longest is in the 
deer-kind. The intestines of a Canadian stag, four 
feet high, measured ninety-six feet*. The intes- 
tine of a sheep, unravelled, measured thirty times 
the length of the body. The intestine of a wild 
cat is only three times the length of the body. 
Universally, where the substance upon which the 
animal feeds is of slow concoction, or yields its 
chyle with more difficulty, there the passage is 
circuitous and dilatory, that time and space may 
be allowed for the change and the absorption 
which are necessary. Where the food is soon 
dissolved, or already half assimilated, an unneces- 
sary or perhaps hurtful detention is avoided, by 
giving to it a shorter and a readier route. 
* Mem. Acad. Paris, 1701, p. 170. 



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NATURAL THEOLOGY. 277 

v. In cpmparing the bones of different animals, 
we are struck, in the bones of birds, with a pro- 
priety which could only proceed from the wisdom 
of an intelligent and designing Creator. In the 
bones of an animal which is to fly, the two quali- 
ties required are strength and lightness. Where- 
in, therefore, do the bones of birds (I speak of 
the cylindrical bones) difiFer in these respects from 
the bones of quadrupeds ? In three properties : 
first, their cavities are much larger in proportion 
to the weight of the bone than in those of qua- 
drupeds ; secondly, these cavities are empty ; 
thirdly, the shell is of a firmer texture than is the 
substance of other bones. It is easy to observe 
these particulars even in picking the wing or leg 
of a chicken. Now the weight being the same, 
the diameter, it is evident, will be greater in a 
hollow bone than in a solid one, and with the 
diameter, as every mathematician can prove, is 
increased, cceteris paribus, the strength of the cy- 
linder or its resistance to breaking. In a word, 
a bone of the same weight would not have been 
so strong in any other form ; and to have made 
it heavier would have incommoded the animal's 
flight. Yet this form could not be acquired 
by use, or the bone become hollow or tubular 
by exercise. What appetency could excavate a 
bone? 



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278 NATUBAL THBQIXI6T. 

VI. The lungs ako of biid% lui ocnspured with 
the lungs of quadrupeds, contnn in then a proiri- 
nou distinguisfamgly cakulated tot this samepiff- 
pose of levkation> naandj, a conmnnniratifin (boI 
found in otlier kinds of animals) betvpeen the air- 
vessek of the lungs and the caTities c^tliebodj; 
so that, by the intromission of air from one to the 
other (at the will, as it diould seem^ of the aoimaL), 
its body can be occasionally puffed out^ and its 
tendency to descend in the air, or its specific 
gratify, nuule less* The bodies of birds are bfewn 
up from their lungs (whidi no other animal bodies 
are), and thus rendered buoyant*. 

VII. All birds are ewpanms. This Uiewise 
carries on the work of gestation with as little in- 
crease sui possible of the weight of the body. A 
graTid uterus would have heen a trouUescme bur- 
den to a bird in its flight The advantage in thas 
respect of an ovrparo«is procreatkm is, that whikt 
the whole brood are hatched together, the eggs 
are excluded singly, and at consid^able mtervahk 
Ten, fifteen, or twenty young birds may be pro- 
duced in one cletch or covey, yet the parent bird 



•• We have thrown some obsarvations upon this sub- 
ject into the Appendix, under the title of '^ The Relaetien 
of the Bodies of Birds to the Atmosphere." 



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NATURAL THEOLOGY. 279 

have never been encumbered l^ the load of Bune 
than one foil-grown egg at one time**. 

VIII. A principal topic of comparison between 
aaumab is in their hutrmnents €f motion. These 
oome befafens nnder three divisions — ^fieet^ wii^^ 
mdfins. I desire any man to say which of the three 
is best fitted fir its use; or whether the same 
eonsnmmate art be not conspicuous in them alL 
The constitution of the elements in which tl» 
motion is to be performed is very different. The 
aooimal action must necessarily follow that consti- 
tntioiiL. The CveatoT, therefore, if we might so 
speak, had to prepare for difier^tit situs^ons, fia 
different difficulties ; yet the purpose is accom- 
plidied not less successfiilly in one case than in 
the other. And as betweoi wmgs and the corre- 
sponding limbs of quadrupeds, it is acc(Hnplished 
without deserting the genial idea. The idea is 
modified, not deserted. Strip a wing of its fea- 
thers, and it bears no obscure resemUance to the 
fore-leg of a quadruped. The articulations at the 
shoulder and the cubitus are mudi alike; and, 

" It has been elsewhere ohserred, that when preda- 
tory birds gorge themselves, they are sometimes nnaUe 
to rise on the wing — a sufficient demonstration ^kat ^le 
burden of an ofi&pring would have unsaited ^lem te 
%fat. 



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280 NATURAL THEOLOGY. 

what is a closer circumstance, in both cases the 
upper part of the limb consists of a single bone, 
the lower part of two. 

But, fitted up with its furniture of feathers and 
quills, it becomes a wonderM instrument, more 
artificial than its first appearance indicates, though 
that be very striking : at least, the use which the 
bird makes of its wings in flying is more compli- 
cated and more curious than is generally known. 
One thing is certain, that if the flapping of the 
wings in flight were no more than the reciprocal 
motion of the same surface in opposite directions, 
either upwards and downwards, or estimated in 
any oblique line, the bird would lose as much by 
one motion as she gained by another. The sky- 
lark could never ascend by such an action as this ; 
for, though the stroke upon the air by the under- 
side of her wing would carry her up, the stroke 
from the upper-side, when she raised her wing 
again, would bring her down. In order, there- 
fore, to account for the advantage which the bird 
derives from her wing, it is necessary to suppose 
that the surface of the wing, measiu*ed upon the 
same plane, is contracted, whilst the wing is drawn 
up ; and let out to its ftill expansion, when it de- 
scends upon the air for the purpose of moving 
the body by the re-action of that element. Now, 
the form and structure of the wing, its external 



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NATURAL THEOLOGY. 281 

convexity, the disposition, and particularly the 
over-lapping, of its larger feathers, the action of 
the muscles and joints of the pinions, are all 
adapted to this alternate adjustment of its shape 
and dimensions. Such a twist, for instance, or 
semirotatory motion, is given to the great fear 
thers of the wing, that they strike the air with 
their flat side, but rise from the stroke slantwise. 
The turning of the oar in rowing, whilst the 
rower advances his hand for a new stroke, is a 
similar operation to that of the feather, and takes 
its name from the resemblance. I believe that 
this faculty is not foimd in the great feathers of 
the tail. This is the place also for observing 
that the pinions are so set upon the body as to 
bring down the wings not vertically, but in a 
direction obliquely tending towards the tail; — 
which motion, by virtue of the common resolution 
of forces, does two things at the same time — sup- 
ports the body in the air, and carries it forward. 
The steerage of a bird in its flight is effected 
partly by the wings, but in a principal degree by 
the tail. And herein we meet with a circum- 
stance not a little remarkable. Birds with long 
legs have short tails; and in their flight place 
their legs close to their bodies, at the same time 
stretching them out backwards, as far as they can. 
In this position the legs extend beyond the rump. 



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282 NATURAL THBOLOQX. 

and beoome the rudder ; supplying that steerage 
which the tail could not. 

From the wings of birds^ the transition is easj 
to they^ of fish.*" They are both, to thm re- 
qpective tribes, the instruments of their moticm; 
but, in the work which they have to do, there is a 
considerable difference, founded in this drcnni- 
stance. Fish, unlike birds> have very nearly 
the same epeeific gravity with the ekment in 
which they move« In the ease of fish, therrfore, 
there is little or no w^gfat to bear up; what is 
wanted, is only an impulse snffident to carry the 
body through a resisting medium* os to majntahi 
the posture^ or to support or resUnre the bahuK^ 

^ Tkis subject is necessarily treated tt kx^^ in the 
Bridgewater Treatise of the Hand* We have had oecsr 
sion to state, that in the higher division of animated 
nature, the vertebrata, cme plan or system of bones can 
be traced through every variety from man to fishes ; 
and this is more especially shovm by the comparison of 
the arm with the anterior extremity of quadnq>eds and 
the wing of birds, and even with the pectoral fin of the 
fish. The number of the bones, and the form and the 
application of the muscles to them vary, but yet they are 
accommodated in a manner so perfect, that, on exa- 
mining any individual among the variefics of the species, 
we should say that nothing could be better suited to its 
purpose. 



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NATURAL THEOLOGY. 283 

of the body, which is always the most unsteady 
where there is no weight to sink it. For these 
offices, the fins are as lai^e as necessary, though 
much smaller than wings, their action mechank»I, 
their position^ and the muscles by which they are 
moved, in the highest degree convenient. The 
following short account of some experiments upon 
fish, made fi^r the purpose of ascertaining the use 
of their fins, will be the best confirmation of what 
we assert. In most fish, besides the great fin, the 
tail, we find two pairs of fins upon the sides, two 
single fins upon the back, and one upon the bcfly, 
or rather between the beUy and the tail. The 
balancing use of these organs is proved in this 
manner. Of the large-headed fish, if you cut off 
the pectoral fins — L e., the pair which lies close 
behind the g^lls — ^the head fells ptme to the 
bottom : if the right pectoral fin only be cut off, 
the fish leans to that side ; if the ventral fin on 
the same side be cut away, then it loses its equi- 
librium entirely ; if the dorsal and ventral fins be 
cut off, the fish reels to the right and left- When 
the fish dies, that is, when the fins cease to play, 
the belly turns upwards. The use of the same 
parts for motion is seen in the following ob- 
servation upon them when put in action. The 
pectoral, and more particularly the ventral fins, 
serve to raise and depress the fish ; when the fish 
desires to have a retrograde motion, a stroke for- 



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284 NATURAL THEOLOGY, 

ward with the pectoral fin efTectually produces it ; 
if the fish desire to turn either way, a single blow 
with the tail the opposite way sends it round at 
once ; if the tail strike both ways, the motion pro- 
duced by the double lash is jyrogressive, and en- 
ables the fish to dart forward with an astonishing 
velocity.* The result is, not only in some cases 
the most rapid, but in all cases the most gentle, 
pliant, easy, animal motion with which we are 
acquainted. However, when the tail is cut off, 
the fish loses all motion, and gives itself up to 
where the water impels it. The rest of the fins, 
therefore, so far as respects motion, seem to be 
merely subsidiary to this. In their mechanical 
twe, the anal fin may be reckoned the keel ; the 
ventral fins, out-riggers; the pectoral muscles, 
the oars ; and if there be any similitude between 
these parts of a boat and a fish, observe, that it is 
not the resemblance of imitation, but the Ukeness 
which arises from applying similar mechanical 
means to the same purpose. 

We have seen that the tail in the fish is the 
great instrument of motion. Now, in cetaceous 
or warm-blooded fish, which are obliged to rise 
every two or three minutes to the surface to take 
breath, the tail, unlike what it is in other fish, is 
horizontal; its stroke, consequently, perpendi- 
cular to the horizon, which is the right direction 
* Goldsmith, Hitt. of An. Nat. vol. vl p. 154. 



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NATURAL THEOLOGY. 285 

for sending the fish to the top, or carrying it down 
to the bottom.** 

^ The poisiDg and motion of fishes in the water has 
interested some of our greatest philosophers, as Gralileo 
and Borelli. It is estimated that fishes make their way 
through a medium which resists nine hundred times 
more than the atmosphere. But then, as it offers a 
certain resistance to their progress, it resists also the 
motion of their tail and fins by which they have their 
power of progression. The breadth of the tail of 
fishes, compared with that of their fins* and its mus- 
cularity and power, declare what is affirmed to us upon 
authority — that the tail is the great instrument of their 
progression ; and we can see that when the trout 
darts away, the force of his motion lays down the fins 
close upon his body. But the fins direct him, as out- 
riggers, and the pectoral fins especially, by raising or 
depressing the head, give direction to the whole body 
under the force of the tail. The lateral fins, and parti- 
cularly the pectoral fins, also sustain him in the right 
position in the water : without the co-operation of these 
with the tail, the fish would move hke a boat sculled by 
one oar at the stem. As the digestion of fishes, as well 
as that of other animals, is attended with the extrication 
of air, and as the intestines are below the centre, the belly 
would be turned up Imt for the action of these lateral fins : 
as we see takes place in a dead fish. The tail and fins 
are the inBfmmentB of m(Akm ; but the inccseant actkm 
of Uic mosdes which move these is a j«st matter <rf ad- 
miimtkMi. If a fifth move with bis bead down the stream. 



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286 NATURAL THEOLOGY. 

Begarding animals in their instruments of 
motion^ we have only followed the comparisoit 

he must move more rapdly than the water, or the water 
gets under the operculum of the gills, and chokes him. 
He HeSy therefore, continually with his head to the stream. 
We may see a trout lying for hours stationary, whilst the 
stream is running past him ; and they seem to remain 
80 for days and nights. In salmon-fishing, the fly is 
played upon the hroken water, in the midst of the torrent» 
and there the fish shows himself rising firom a part of the 
river where men could not preserve their footing, though 
assisted hy poles, or hy locking their arms together. 
When the salmon leaps, he makes extraordinary exer- 
tions. Just under the cataract, and against the stream, 
he will rush for some yards, and rise out of the spray 
six or eight feet ; and amidst the noise of the water, they 
may he heard striking against the rock with a sound like 
the clapping of the hands. If they find a temporary lodg- 
ment on the shelving rock, they lie quivering and pre- 
paring for another somerset, until they reach the top of 
the cataract. This exhihits not only the power of their 
muscles, assisted hy the elasticity of their hones, hut the 
Ibrce of instinct hy which they are led to seek the shallow 
streams for depositing their eggs. 

The porpoise will swim round and round a ship which 
is sailing at fourteen miles an hour : a thing almost as 
surprising as the fly circling round the horse's ear for a 
whole stage. 

To all this may he added, that the solid which mathe- 
maticians have discovered, hy refined aj^Ucation of the 



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NATURAL THEOLOGY. 287 

through the ftrst gieat division of animals into 
beasts, birds, and fish. If it were oiir intention 
to pursue the consideration farther, I should take 
in that generic distinction amongst birds, the web- 
foot of water-fowL It is an instance which may be 
pointed out to a child. The utility of the web to 
wat^-fowl, the inutility to land-fowl, are so ob- 
vious, that it seems impossible to notice the dif- 
ference without acfaiowledging the design. I am 
at a loss to know how those who deny the agency 
of an intelligent Creator dispose of this example. 




Tliere is nothing in the action of swimmings as 
carried on by a bird upon the surface of the water, 
that should generate a membrane between the 
toes. As to that membrane, it is an exercise of 
constant resistance. The only supposition I can 
think of is, that all birds have been originally 



calculus, and have tenned ^^ the solid of least resistance,'' 
because it is the confonnation which is less than any 
other affected bj the resutance of any medium, resem- 
Ues a fidi in its fonn* 



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288 NATURAL THEOLOGY. 

water-fowl, and web-footed ; that sparrows, hawks, 
linnets, &c., which frequent the land, have, in 
process of time, and in the course of many genera- 
tions, had this part worn away by treading upon 
hard ground. To such evasive assumptions must 
atheism always have recourse ! And after all, it 
confesses that the structure of the feet of birds, in 
their original form, was critically adapted to their 
original destination ! The web-feet of amphibious 
quadrupeds, seals, otters, &c., fall under the same 
observation. 

IX. The fitoe senses are common to most large 
animals ; nor have we much difference to remark 
in their constitution, or much, however, which is 
referable to mechanism. 

The superior sagacity of animals which hunt 
their prey, and which, consequently, depend for 
their livelihood upon their nose, is well known in 
its use ; but not at all known in the organization 
which produces it. 

The external ears of beasts of prey, of lions, 
tigers, wolves, have their trumpet -part, or con- 
cavity, standing forwards, to seize the sounds 
which are before them — ^viz., the sounds of the 
animals which they pursue or watch. The ears of 
animals of flight are turned backward, to give 
notice of the approach of their enemy from behind, 
whence he may steal upon them unseen. This is 
a critical distinction, and is mechanical; but it 



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NATURAL THEOLOGY. 



289 



may be suggested, and, I think, not without pro- 
bability, that it is the effect of continual habit. 




The eyes ot animals which follow their prey by 
night, as cats, owls, &c., possess a faculty not 
given to those of other species, namely, of closing 
the pupil entirely. The final cause of which 
seems to be this: — It was necessary for such 
animals to be able to descry objects with very 
small degrees of light. This capacity depended 
upon the superior sensibility of the retina ; that 
is, upon its being eflTected by the most feeble im- 
pulses. But that tenderness of structure, which 
rendered the membrane thus exquisitely sensible, 
rendered it also liable to be offended by the access 

o 



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290 NATURAL THEOLOGY. 

c^ gtron^r degrees of light The contractile 
range therefore of the pupl is mcrcased in these 
animals, so as to enable them to close the aperture 
entirely, which includes* dber fomer of diminishing 
it in every degree;. where)>}r st all times such 
portions, and only sux^ portioasy of light are 
admitted, as may he received without injury to 
the sense. 




[The figure represents the iris of a lion. B B, the 
straight op eonverging fibres ; C, the fibres which en- 
circle the inner margin of the iris.] 

There appears to be abx) in the figure, and in 
some piK^perties of the pupil of the eye, an appro- 
pri«te velatioit to the wants of different animala. 
In; horses^ oxen;, goats». £^ep, the pupil- of the eye 
k eUaptical ;. the transverse axis- being horizontal ; 
by which structure, although the eye be placed 
on the side of the head, the aatericHr elotigatk>a of 
the pnpii caitcfaies the forward rays, or t^se which 
come frons objecte izniDedaately i» front ef the 
animal's &ce. 



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NATURAL THEOLOGY. 291 



CHAPTER XIIL 

PECULIAR ORGANISATIONS. 

I BELiETE tkat all the instanceft whieh I shall col- 
lect under this title might, consistemily enoag^ 
with tedinieal langus^e, have been placed tmder 
the I^ad oi Comparaiive Ancdomy. But there 
appears to me an impropriety in the use which 
that term hatih obtained; it being, in some sort, 
absurd to call that a case of comparative anatomy, 
in whieh there is nothing to '^ compare;" in which 
a conformation is Sound in one animal, which hath 
nothing properly answering to it in another. Of 
this kind are the examples which I have to |»o- 
pose in the present chapter; and the reader will 
see that, though some of them, be the strongest, 
perhaps, he will meet with under any divisicm c£ 
<mr mibject, they must neeessarily be of an uKcoor 
Biected and miscellaneoas nature. To diiqpose 
them» howeirer, into some sort of order, we wift 
Botice,^ first, particularities of strueture whidi 
belong to quadrupeds, birds, and fish, as such, or 
to many of the hinds included in these classes of 
MJniafa; and then, sudb partieulaarities as are 
eon&ied to one oc two species. 

o2 



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292 NATURAL THEOLOOY. 

I. Along each side of the neck of large quadru- 
peds runs a stiff robust cartilage^ which butchers 
call the pax-wax. No person can carve the upper 
end of a crop of beef without driving his knife 
against it. It is a tough, strong, tendinous sub- 
stance^ braced from the head to the middle of the 
back: its office is to assist in supporting the 
weight of the head. It is a mechanical provision, 
of which this is the undisputed use; and it is 
sufficient, and not more than sufficient, for the 
purpose which it has to execute. The head of an 
ox or a horse is a heavy weight, acting at the end 
of a long lever (consequently with a great pur- 
chase), and in a direction nearly perpendicular to 
the joints of the supporting neck. From such a 
force, so advantageously applied, the bones of the 
neck would be in constant danger of dislocation, 
if they were not fortified by this strong tape. No 
such organ is found in the human subject, be- 
cause, from the erect position of the head (the 
pressure of it acting nearly in the direction of the 
spine), the junction of the vertebrae appears to be 
sufficiently secure without it. This cautionary ex- 
pedient, therefore, is limited to quadrupeds : the 
care of the Creator is seen where it is wanted*'. 

^ Th6 author is not quite correct here, inasmuch as 
elastic ligaments are liberally supplied in the human 



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NATURAL THEOLOGY. 293 

II. The oil with which bird^ preen their fea- 
thers, and the organ which supplies it, is a specific 
provision for the winged creation. On each side 
of the rump of birds is observed a small nipple, 
yielding upon pressure a butter-like substance, 
which the bird extracts by pinching the pap with 
its bill. With this oil or ointment, thus procured, 
the bird dresses his coat ; and repeats the action 
as often as its own sensations teach it that it is in 
any part wanted, or as the excretion may be suf- 



spine : a range of peculiar ligaments, the " ligamenia sub' 
jlava^* run along the course of the spine, and are highly 
elastic. The ligamentum nuchce is that ligament which 
runs from the prominence of the spine between the shoul- 
ders to the back of the head ; and the student who hangs 
his head over his book enjoys the advantage of this elas- 
tic support : so that it is strictly a matter comparative ; 
we may trace it with increasing strength from the liga- 
ment that sustains a man's head, to that which, like 
the spring of a steelyard, weighs against the immense 
head of the elephant. 

These elastic hgaments vary with the length and 
motion of the neck. It would be tedious to describe 
their varieties in the camel, cameleopard, ostrich, &c. 
We may be satisfied with the fact, that the elastic liga- 
ment is a structure extensively used in the animal tex- 
tures, generally coming in aid of the muscles, or as a 
substitute for them. 



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294 NATURAL TUBOLOGT. 

ficient fi>r the expense. The gland, the pap, fiie 
nature and quality of the excreted substance, 
the manner of obtaining it from its lodgment in 
the body, the application of it when obtained, 
fiorm, adlectively, an e\Tdence of intention which 
it is not easy to withstand. Nothing similar to 
it is found in unfeathered animals. What blind 
cmiaiMs of nature should produce it in birds; 
diould not produce it in beasts ? 

III. The idr-bladder also of a fi^ affords a 
plain and direct instance, not only of contrivance, 
but strictly of that species of contrivance which 
we denominate mechanical. It is a philosophical 
apparatus in the body of an animal. The prin- 
ciple of the contrivance is clear : the application 
of the principle is also clear. The use of the 
organ to sustain, and, at will, also to elevate, the 
body of the fish in the water, is proved by ob- 
serving, what has been tried, that, when the 
bladder is bursty the fish grovels at the bottom ; 
and also, that flounders, soles, skates, wfatdb axe 
without the air-bladder, seldom rise in the water, 
and that with effi»t. The manner in which ihe 
purpose is attained, and the suitableness of Ute 
means to the end, are not difficult to be appre- 
hended. The rising and sinking of a fish in 
water, so far as it is independent of the stroTte 
of the fins and tail, can only be regulated by the 
specific gravity of the body. When the bladder. 



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KATURAL tTHEOLOOr. 295 

coataiBed in fiie body of tke fish, is ^autracrtol^ 
wliich the fifili probably possesses a snusculor 
power of doing, the bulk of the fish is contaracted 
along with it ; whereby^ since the absolute «/eighi 
remains the same, the specific gravily, whidi is 
the skaking force, is increased, and the fish de^ 
scends: on the contrary, when, m c<mseqiienoe 
of the relaxation of the mnscles, the ela^oity of 
the enclosed and now compressed air restores tho 
dimensions of the bladder, the tendency down* 
wards becomes proportionably less than it warn 
before, or is turned into a contrary tendency. 
These are known properties of bodies immersed 
in a fluid. The enamelled figures, or little glass 
bubbles, in a jar of water, are made to rise and 
fall by the same artifice. A diving-macbine 
might be made to ascend and descend, upo^ 
the like principle; namely, by introducing into 
the ini^e of it an air-vessel, which, by its cowi' 
traction, would diminish, and by its distenskm 
enlarge, the btdk of the machine itself, and thus 
render it specifically heavier or specifically lighter 
than the water which surrounds it. Suppose this 
to be done, and the artist to solicit a patent for 
his invention : the inspectors of the model, what- 
ever they might think of the use or value of the 
contrivance, could by no possibility entertain a 
question in their minds, whether it were a con- 
trivance ox not. No reason has ever been as- 



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296 NATURAL THEOLOGY. 

signed, — no reason can be assigned, why the con- 
clusion is not as certain in the fish as it is in the 
machine ; why the argument is not as firm in one 
case as the other. 

It would be very worthy of inquiry, if it were 
possible to discover, by what method an animal 
which lives constantly in water is able to supply 
a repository of air. The expedient, whatever it 
be, forms part, and perhaps the most curious 
part of the provision. Nothing simili^ to the 
air-bladder is found in land-animals ; and a life 
in the water has no natural tendency to produce 
a bag of air. Nothing can be farther from an 
acquired organisation than this is **. 

*• The sea varies in temperature and pressure at dif- 
ferent depths, and no doubt the texture of the fish, and 
especially of its integument, must conform to this va- 
riety. The swimming-bladder is the means of adjust- 
ment by which the fish lives at its native depths without 
waste of animal exertion : such is the power of expansion 
of the air-bladder when relieved from Che pressure, that, 
when a fish is brought up from the greatest depth, it in- 
verts and thrusts out the viscera from the mouth. We 
do not see, however, that naturalists have adverted to 
the place of this swimming-bladder. It lies close to 
the spine, and appears to counterbalance, in some mea- 
sure at least, the air in the intestines by being thus placed 
above them. In the cetacea, as the whale, their buoy- 
ancy proceeds from the quantity of oil under the skin, 



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NATURAL THEOLOGY. 297 

These examples mark the attention of the 
Creator to the three great kingdoms of his ani- 
mal creation, and to their constitution as such. — 
The example which stands next in point of gene- 
rality, belonging to a large tribe of animals, or 
rather to various species of that tribe, is the poi- 
sonous tooth of serpents. 

I. The fang of a viper is a clear and curious 
example of mechanical contrivance. It is a per- 
forated tooth, loose at the root ; in its quiet state, 
lying down flat upon the jaw, but furnished \vith 
a muscle, which, with a jerk, and by the pluck, as 
it were, of a string, suddenly erects it. Under 
the tooth, close to its root, and communicating 
with the perforation, lies a small bag containing 
the venom. When the fang is raised, the closing 
of the jaw presses its root against the bag under- 

especially of their head, and which it has been observed 
is bestowed in order to ensure their readily coming to 
the surface to breathe when their natural powers are 
weakened. For the same reason, that they may raise 
their heads to the surface, their tails are horizontal. In 
the jelly-fish, those soft animals which float in sheltered 
estuaries (the physsophord)^ there is an air-vessel which 
they can fill and empty, by which means they rise or 
sink at pleasure. Others (the villela) raise a sail. 
Some of this class propel themselves by taking in water, 
and suddenly rejecting it. 

o 3 



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fSb MATUBAL THB0L06T. 



%ih ; and the foiee of this compression sends 
out the fluid with a considerable impetus through 
the tube in the middle of the tooth. What move 
unequivocal or effectual apparatus could be de- 
yised ior the double purpose of at once inflictiBg 
the wound and injecting the poison ? Yet, thoogh 
lodged in the mouth, it is so constituted, as, in its 
inoffensire and quiescent state, not to interfere 
with the animal's ordinary office oi receiving its 
food. It has been observed also* that none of 
the harmless serpents, the black snake, the blind 
worm,&c^have these &ngs, but teeth of an equal 
size ; not moveable as this is, but fixed into the 
jaw. 

IL In being the property of several differoit 
npedes, the preceding example is resembled by 
that whidi I shall next mention, which is the bag 
of the opofsum. This is a mechanical contrivance, 
most properly so called. The simplicity of the 
expedient renders the contrivance more obvious 
than many others, and by no means less certain. 
A false sMn under the belly of the animal forms 
a pouch, into which the young litter are received 
at their birth ; where they have an easy and con- 
stant access to the teats ; in which they are trans* 
ported by the dam from place to place; wh^e 
they are at liberty to run in and out ; and where 
they find a refuge from surprise and danger. It 
is their cradle, their asylum, and the machine for 



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NATURAL THEOLOGY, 299 

tbeir conv^ance. Can the wse of this stiructure 
be doubted of ? Nor is it a mere doubling of the 
skin; but is'a new orgWEL, furnished with bones 
nmd muscles of its own. Two bones are placed 
b^re the os pubis^ and joined to that boue as 
their base. These support and giT« a fixture to 
the muscles whkdi serve to opeai the bag. To 
these muscles there are antagonists, whidi s^re 
i& the same manster to shut it; and this office 
they perform so exactly, iJaat, in the living anijaajU 
the qp^ng can scarcely be discerned, exoeft 
when the sides are forcibly drawn asunder*. Is 
there any action in this part of the animal, any 
process arising firom that action, by which these 
members oould be formed? any account to be 
given of the f(C»*mation, except design ? 

III. As a particularity, yet appertaining to 
more species than one, and also as strictly me- 
chanical, we may notke a circums^nce in the 
structure of the daws of certain biids. The mid- 
dle claw of the heron and cormorant fe toothed 
and notched like a saw. These birds are great 
fishes, and these notches assist them in holding 
their slippery prey. The use is evident; but 
the structure such, as cannot at aU be accounted 
for by the effort of the animal, <Mr the exercise of 
the part Some other fishing birds have these 
notches in their bills ; and for the same purposa 

* Ocadmmfli, Nat Hiat. v<d. W. p. 344. 



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900 NATURAL THEOLOGY. 

The gannet, or Soland gooae, has the side of its 
bill irregularly jagged, that it may hold its prey 
the faster. Nor can the structure in this, more 
than in the former case, arise 'from the manner 
of employing the part. The smooth surfaces, and 
toft flesh of fish, were less likely to notch the bills 
of birds, than the hard bodies upon which many 
other species feed. 

We now come to particularities strictly so 
called, as being limited to a single species of 
animal. Of these, I shall take one firom a qua- 
druped, and one from a bird. 

1. The stomach of the camel is well known to 
retain large quantities of water, and to retain it 
unchanged for a considerable length of time. 
This property qualifies it for living in the desert. 
Let us see, therefore, what is the internal orga- 
nisation, upon which a faculty so rare and so 
beneficial depends. A number of distinct sacs 
or bags (in a dromedary thirty of these have been 
counted) are observed to lie between the mem- 
branes of the second stomach, and to open into 
the stomach near the top by small square aper- 
tures. Through these orifices, after the stomach 
is full, the annexed bags are filled from it : and 
the water so deposited is, in the first place, not 
liable to pass into the intestines ; in the second 
place, is kept separate from the solid aliment; and, 
in the third place, is out of the reach of the diges- 



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NATURAL THEOLOGY. 301 

tive action of the stomach, or of mixture with 
the gastric juice. It appears probable, or rather 
certain, that the animal, by the conformation of its 
muscles, possesses the power of squeezing back 
this water from the adjacent bags into the sto- 
mach, whenever thirst excites it to put this power 
in action. 

II. The tongue of the woodpecker is one of those 
singularities, which nature presents us with, when 
a singular purpose is to be answered. It is a par- 
ticular instrument for a particular use ; and what, 
except design, ever produces such ? The wood- 
pecker lives chiefly upon insects lodged in the 
bodies of decayed or decaying trees. For the 
purpose of boring into the wood, it is furnished 
with a bill straight, hard, angular, and sharp. 
When, by means of this piercer, it has reached 
the cells of the insects, then comes the office of 
its tongue : which tongue is, first, of such a length 
that the bird can dart it out three or four inches 
from the bill, — ^in this respect differing greatly 
from every other species of bird ; in the second 
place, it is tipped with a stiff, sharp, bony thorn ; 
and, in the third place (which appears to me the 
most remarkable property of all), this tip is den- 
tated on both sides like the beard of an arrow or 
the barb of a hook. The description of the part 
declares its uses. The bird, having exposed the 



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902 NATURAL THSOLOOT. 

lutreats of tlieuisects by tbeaanstanceof its bill, 
with a ttotkm inconeeivaUy quick, btuBcbes <Nti 
at them this long tcmgue ; transfixes them upon 
the barbed needle at the end of it; and thus 
draws its prey within its mouth. If this be not 
meehanism, what is ? ^lould it be said, that, by 
continual eadeavours to shoot out the tongt» to 
the stretch, the woodpecker species may by degrees 
kaye lengthened the organ itadf, bejrond ihst of 
other birds, what accoont can be given of its form, 
of its tip? how, in particular, did it get its barb, 
its dentation ? These barbs, in my opinion, wheve- 
ever they occur, are decisive procrfs of meclomiad 
contrivance*. 

^ What could have tempted Bufibn to express Ins 
pity for this bird as abject and degraded, it is not easy to 
conceive : nor why it should be described as leading an 
insipid life, because continually employed in boring and 
hammering the old stump of a tree. A late naturalist 
describes the woodpecker as enjoying the sweet hours of 
the morning, on the highest branch of the tallest tree, 
fluttering and playing with his mate and companions. 
No doubt his diligence, perseverance, and energy in 
plying his beak is very extraordinary. But, besides the 
wedge-Kke strength of the beak, and the power of the 
neck to strike with it, there is something remarkable in 
its sensibility. That nerve, the fifth pair, on which we 
have shown that all the sensibility of <he head depends. 



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N1.TURAL THEOLOGY. 303 

III. I shall add one more example, for the sake 
of its novelty. It is always an agreeable discovery. 



transmits a large branch along the insiJe of the man- 
dibles : and, as this nerve approaches liie extremity, it 
perforates the bone by innumerable Mnall canals, so as 
to be given to the homy covering of the beak, which is 
thus possessed of a sensibility to kstl in the crevices of 
the wood, and under the bark; asd the woodpecker is 
enabled by this means to dkect Ube tongue, which our 
author correctly describes m moving with extraordinary 
celerity, and with a point Wa^ m ferbed arrow. 

We have represented 1^ dissection of the head of 
this bird more accurately in its anatomy than is to be 
found in bopks. We o^r it because it exhibits a very 
curious piece of mecianiBm, adj^ted to the tongue, to 
enable the animal to thruBt it out far, and with unusual 
rapidity. A, is the barbed tongue; B, two slender elastic 
ligamentous cartilages, oi vay peculiar structure and use. 
On one extremity they are attaclied to the bone which 
supports the upper mandible ; fi?om this we trace them 
over the skull down upon the sides of the neck ; and, 
with a large sweep, turning under the lower mandible, 
and so continued into the tongue, and not terminating 
until they reach the horny point. C C C, a long muscle 
which follows these ligamentouB cartilages upon their con- 
cave side, arising from the bone «f the lower mandible, 
and so sweeping round with the cartilages and over the 
skull, to have another fixed point at the upper mandible: 



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304 



NATURAL THEOLOGY. 




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NATURAL THEOLOGY. 905 

when^ having remarked in an animal an extraor- 
dinary structure, we come at length to find out 



these protrude the tongue. Two muscles are seen to 
arise from the sides of the larynx, which are the 
opponents of the last, and retract the tongue. Leav- 
ing the other parts of the anatomy, we heg the reader's 
attention to the action of the muscle C C C, which 
presents one of those curious instances observed in 
comparative anatomy, of a mechanism adapted to a 
particular purpose. The tongue is not only thrust 
out far by this apparatus, but is shot with great 
rapidity, in correspondence with its barbed point. This 
effect is produced by the two extremities of the muscle 
being fixed points, and the fibres of the muscle itself 
running on the concave side of the cartilaginous bow, 
so as to form a smaller circle. We require no ma- 
thematical demonstration to prove that the tongue must 
be thrust out to a greater distance than the measure 
of contraction of the muscle. Let us tie the line of 
the fishing-rod to its slender top, and pull upon it at 
the butt : the motion of the top will be very extensive, 
even when only an inch of the line is drawn through 
the rings. This is a pretty accurate representation of 
what takes place by the contraction of this protruding 
muscle. We have noticed that the upper end of this 
arch is fixed, the whole motion must therefore be given 
to the loose extremity in the tongue; and we cannot 
but observe that this peculiar arch and muscular ring 



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a06 NATURAL TmSOIiOGT* 

an unexpected use £ar it. Hi^ fioUomng man- 
Hve fiimkliefl an instaaoe of Hob kind. The 
babyroussa^ or Indian hog, a species of wild 
boar> found in the East Indies^ has two bent teeth^ 
more than half a yard long, growing upwards, 
and {whicii is <lie singtdarity) from the upper 
jaw. These instruments are not wanted for 
offence; that service being provided for by two 
tusks issuing from the under jaw, and resembling 
those of the common boar : nor does the animal 
use them for defence. They might seem, there- 
fore, to be both a superfluity and an encumbrance. 
But observe the event : — ^the animal sleeps stand- 
are ada|>ted for tbe rapid protrusion of the tongue , wli^ 
its retraction is produced by a common muicle, th«tifi,A 
muscle nmning in a straight course. 

Another curious part of this apparatus is, that a vesj 
laxgt gland, whicb pours out a glutinous matter, is em- 
braced and compressed by the action of tike circular 
muscle. This Tiscid secretion bedewing the tongue 
furnishes an additional means for the bird to pick v^ 
insects, such as ants, without the necessi^ of sticking 
each with its arrow. Nothing can be more mechanical, 
or more happily adapted to its purpose, than the whole 
of this structure, and consequently nothing better suited 
to strengthen the argument in the text. Indeed it is not 
inferior to the means employed for giving rapidity of mo- 
tion to the membrana nicHtans of the eye of the bird. 



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NATURAL THEOLOGY. 



3D7 



ing; and, in order to support its head, hooks its 
upper tusks upon the branches of trees**. 




^ This notion of the babyroussa sleeping on its feet 
and hanging by its teeth the while, is a mere fiancy. 
It has arisen from the difficulty of accounting for the 
teeth, which rise out from the mouth, and turn up before 
the eyes. The better opinion is, that they guard the eyes 
in rushing through the thick underwood. 



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306 NATURAL THE(HXX3T* 



CHAPTER XIV. 

PROSPECTIVE CONTRIVANCES. 

I CAN hardly imagine to myself a more distin- 
guishing mark^ and, consequently, a more certain 
proof of design, than preparation, — i. e,, the pro- 
viding of things beforehand, which are not to be 
used until a considerable time afterwards: for 
this implies a contemplation of the future, which 
belongs only to intelligence. 

Of these prospective contrivances, the bodies of 
animals fiimish various examples. 

I. The human teeth aflTord an instance, not 
only of prospective contrivance, but of the com- 
pletion of the contrivance being designedly sus- 
pended. They are formed within the gums, and 
there they stop ; the fact being, that their farther 
advance to maturity would not only be useless to 
the new-bom animal, but extremely in its way ; 
as it is evident that the act of suckingy by which 
it is for some time to be nourished, will be per- 
formed with more ease both to the nurse and to 
the infant, whilst the inside of the mouth and 



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NATURAL THEOLOGY. 309 

edges of the gums are smooth and soft, than if 
set with hard-pointed bones. By the time they 
are wanted the teeth are ready. They have 
been lodged within the gums for some months 
past^ but detained, as it were, in their sockets, so 
long as their farther protrusion would interfere 
with the office to which the mouth is destined. 
Nature, namely, that intelligence which was em- 
ployed in creation, looked beyond the first year 
of the infant's life ; yet, whilst she was providing 
for functions which were after that term to become 
necessary, was careful not to incommode those 
which preceded them. What renders it more 
probable that this is the effect of design, is, that 
the teeth are imperfect, whilst all other parts of 
the mouth are perfect. The lips are perfect, the 
tongue is perfect ; the cheeks, the jaws, the palate, 
the pharynx, the larynx, are all perfect : the teeth 
alone are not so. This is the fact with respect to 
the human mouth : the fact also is, that the parts 
above enumerated are called into use from the 
beginning ; whereas the teeth would be only so 
many obstacles and annoyances, if they were there. 
When a contrary order is necessary, a contrary 
order prevails. In the worm of the beetle, as 
hatched from the egg, the teeth are the first 
things which arrive at perfection. The insect 
begins to gnaw as soon as it escapes from the 



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310 NATiniAL THEOLOOT. 

fineQ, though its other parts be •nfy graduoBy 
adrancnig to their matirrity *. 

What has been observed of the teeth, is tmc 
of the horns of animals; and for the same reason:. 
The horn of a calf or a lamb does not bttd, or at 
least does not sprout to any consklerable length, 
mill the animal be eapable of browsing upon its 
pasture ; beeause snch a substance upon the fore^ 
head of the young animid would rery much m- 
comnode the teat of the dam in the office of 
girhig suck. 

But in the case of the ieetk—i^ the human 
leeth at least, the prospectrre contrivance looks 
slin &rth«r. A succession of crops is proridet^t 
and provided from the beginning; a second tier 
being originally formed beneath the first, winch 
do not come into use till several years afterward. 
And this double or suppletory provision meets a 
difficulty in the mechanism of the mouth, wbiA 
would have appeared almost insurmountable. 
The expansion of the jaw (the consequence of the 
proportionable growth of the animal, and of its 
skull) necessarily separates the teeth of the first 
set, however compactly disposed, to a distance from 
cme another, which would be very inconvenient. 

* See the note upon the teeth in the Appendix. The 
subject is full of interest. 



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X^ATUBAl. THEOLOGY. 311 

Ia due tiizi^ the^e&se, i. e., when the jsm hsm 
aJttained a grea4; part of ifes dimensiiHis^ a new s^ 
of teeth springs up (loosening syid pushing out 
the old e»es before them)^ more exactly fitted to 
the spaee whdeh they are to occupy^ and risiisg 
also in such close ranks^ as to allow ior any exteu- 
tton of line which the subsequent enlargement of 
the head may occasicm.''^ 

III. It is not very easy to c^iceive a more evi- 
denily prospective coatrivance than that which, 
in all viviparous animals^ is found in the milk of 
the female parent. At the moment the young 
animal enters the world there is its maiutenanee 
ready for it. The particuhirs to be remdurked in 
this economy are neither few nor sHght. We 
have^ firsts the nutritious quality o£ the ftuid» 
unlike, in this respect, every other excretion (rf 
the body ; and in which nature hitherto remains 

•* The second or permanent set of teeth does not push 
out the deciduous or milk teeth. The process is not 
mechanical. Whilst yet a tender membrane is around 
the second tooth, those of the first set are suffering ab- 
sorption at their fangs. Another circumstance, which 
shows the provision not to be mechanical, is the wasting 
of the old alveolar process, and the growth of the new : 
the new alveolar process or socket of the permanent tooth 
is forming at the time that the portion of the jaw whidi 
held the first tooth firm ia yieldmg by absorption. 



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312 NATURAL THEOLOGY. 

unimitatcd, neither cookery nor chemistry having 
been able to make milk out of grass : we have, 
secondly, the organ for its reception and retention: 
we have, thirdly, the excretory duct annexed to 
that organ : and we have, lastly, the determination 
of the milk to the breast at the particular junc- 
ture when it is about to be wanted. We have 
all these properties in the subject before us ; and 
they are all indications of design. The last cir- 
cumstance is the strongest of any. If I had been 
to guess beforehand, I should have conjectured, 
that at the time when there was an extraordinary 
demand for nourishment in one part of the sys- 
tem there would be the least likelihood of a re- 
dimdancy to supply another part. The advanced 
pregnancy of the female has no intelligible ten- 
dency to fill the breasts with milk. The lacteal 
system is a constant wonder ; and it adds to other 
causes of our admiration, that the number of the 
teats or paps in each species is found to bear a 
proportion to the number of the young. In the 
sow, the bitch, the rabbit, the cat, the rat, which 
have numerous litters, the paps are numerous, 
and arc disposed along the whole length of the 
belly : in the cow and mare, they are few. The 
most simple account of this, is to refer it to a de- 
signing Creator •*. 

^^* The only parallel to this is the care with which 



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NATURAL THEOLOGY. 313 

But in the argument before us, we are entitled 
to consider not only animal bodies when framed, 
but the circumstance under which they are 
framed: and in this view of the subject, the con- 
stitution of many of their parts is most strictly 
prospective. 

nature secures the nourishment of the embryon plant, 
or the chick in the ^g. The lobes of a bean or a pea, 
and of most seeds, consist of a deposit of nutritious mat- 
ter, and when heat and moisture favour the development 
of the Uving property, vessels which are scattered in these 
lobes or cotyledons commence absorption of the matter, 
and carry it to the centre of the plant. It is remark- 
able that these lobes, having thus, in the first instance, 
supplied the young plant with nutritious matter, change 
their office, and, rising above the surface, become the 
first leaves. Thus we see how the nourishment is sup- 
plied, until the radicle is pushed down into the earth, 
and the leaves receive the influence of the atmosphere. 
So in the chick, the white or albumen of the eg^ goes to 
its nourishment whilst it is in the shell : but the yolk 
of the egg is embraced in the body of the chick when 
excluded from the shell, and a duct leads from the mem- 
brane enclosing this mass of nutriment into the first 
intestine. And thus is the chick nourished, not only 
whilst included in the shell, but also during its first 
feeble existence, a period which corresponds with that 
of lactation in mammalia. 

p 



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314 KATURAL THBOLOCnr. 

' in. The eye is of no iise> at tlie tisie wken it 
is formecL It is an optieal instrument made in a 
dungeon; construct^ for the refira^ionof ligh^ 
to a focus, and perfect Ibr its purpo6e>, bef^^re a 
ray of liglit has h^d access to il ; ge(Nnetrica% 
adapted to the properties and action of an de- 
ment> with which it has no communication. It is 
about indeed to enter into that communication : 
and this is jnrecisely the thing which evidences 
intention. It is providing for the future in the 
closest sense which can be given to these terns.; 
for it is providing for a future change ; not fi)r the 
then subsisting condition of the animal; not for 
any gradual progress or advance in that same 
condition; but for a new state, the consequence 
of a great and sudden alteration, which the animal 
is to undergo at its birth. Is it to be believed 
that the eye was formed, or, which is the same 
thing, that the series of causes was fixed by which 
the eye is formed, without a view to this change ; 
without a prospect of that condition, in which its 
fabric, of no use at present, is about to be of the 
greatest ; without a consideration of the qualities 
of that element, hitherto entirely excluded, but 
with which it was hereafter to hold so intimate a 
relation ? A young man ms^es a pair of spec- 
tacles for himsdf against he grows old; for which 
spectacles he has no want or use whatever at tte 



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NATURAL THEOLOGY. 315 

time he makes them. Could this be done without 
kaowing a&d considering the defect of viid(»iif to 
vAmh advtmced age is subject ? Would not the 
precise siiiitableness of the instrum^it to its piu> 
pose^ of the remedy to the defect^ of the convex 
l»is to the &iitened eye^ establish the certainty 
of the concluskm> that the case, afterwards to 
anse, had been cc^asidereld beforehand^ speculated 
upon, provided fer ? all which are exclusively ths 
sets of a reasoniitg mind. The eye formed in one 
stsite, for use only in an%)ther state, and in a (Uf* 
ferent state, affoards a proof no less dear c^ desti* 
nation to a fbture purpose ; and a proof proper- 
tionably stronger, as tl^ machinery is more com- 
plkated, and the adaptation more exact. 

IV. What has been said of the eye, hcdds 
equally true of the lungs. Composed of aie- 
Vess^s, where there is no air; el^^rately con* 
ftlructed for the alten^^e admissicm and expulsion 
of an elastic ftuid, where no sueh fluid exists ; tlm 
great organ, with the whole apparatus belonging 
to it, lies collapsed in the fcetal thorax ; yet ii^ 
order, and in readiness for action, the first mo- 
ment that the occasion requires its service. This 
is having a machine locked up in store for fntuxe 
tise; i¥hich incontestably proves, that the case 
was expected to occur in which this use might be 
experienced; but expects^n is the proper act of 

p 2 



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316 NATURAL THEOLOGY. 

intelligence. Considering the state in whicli an 
animal exists before its birth, I should look for 
nothing less in its body than a system of lungs. 
It is like finding a pair of bellows in the bottom 
of the sea; of no sort of use in the situation in 
which they are found ; formed for an action which 
was impossible to be exerted ; holding no relation 
or fitness to the element which surrounds them, 
but both to another element in another place. 

As part and parcel of the same plan ought to 
be mentioned, in speaking of the lungs, the pro- 
visionary contrivances of the foramen ovale and 
dtictus arteriosus. In the foetus pipes are laid 
for the passage of the blood through the lungs ; 
but, until the lungs be inflated by the inspira- 
tion of air, that passage is impervious, or in a 
great degree obstructed. What then is to be 
done? What would an artist, what would a 
master, do upon the occasion? He would en- 
deavour, most probably, to provide a temporary 
passage, which might carry on the communication 
required, until the other was open. Now this is 
the thing which is actually done in the heart. 
Instead of the circuitous route through the lungs 
which the blood afterwards takes before it get 
from one auricle of the heart to the other, a por- 
tion of the blood passes immediately fix>m the 
right auricle to the left, through a hole placed 



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NATURAL THEOLOGY. 317 

in the partition which separates these cavities. 
This hole anatomists call the foramen ovale. 
There is likewise another cross cut^ answering 
the same purpose, by what is called the ductus 
arteriosus, lying between the pulmonary artery 
and the aorta. But both expedients are so 
strictly temporary, that after birth the one pas- 
sage is closed, and the tube which forms the 
other shrivelled up into a ligament. If this be 
not contrivance, what is ? 

But, forasmuch as the action of the air upon 
the blood in the lungs appears to be necessary to 
the perfect concoction of that fluid, i. e, to the life 
and health of the animal (otherwise the shortest 
route might still be the best), how comes it to 
pass that the foetus lives, and grows, and thrives 
^without it ? The answer is, that the blood of the 
foetus is the mother's; that it has undergone that 
action in her habit; that one pair of lungs serves 
for both. When the animals are separated a new 
necessity arises ; and to meet this necessity as 
soon as it occurs an organisation is prepared. It 
is ready for its purpose; it only waits for the 
atmosphere; it begins to play the moment the 
air is admitted to it •*. 

•• Does not the whole condition of the embryon go to 
this argument? At first there is a mere jelly, or what 



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318 NATUBAL THMOLOar. 

apftKn as such ; a Htde ^ur&er adyaaood, and tiieit 
are bones, and miBclea, and aerfita* But these lie 
fHvitt inactive for a long teitn ; tbe xierve exdtes to do 
adaoo ; the muscles do not BM>ve; the joints are not 
tttercised, they aie perfected sbwly. The period of fiill 
development is not arrived; th^ have not yet their 
stnnulug to activity. The "whole then is in a state of 
preparation. Conduit pipes vdthout their fluids, glands 
and ducts without their secretions, sensibilities dormant, 
and a mechanism quite inoperative; a whole animal 
system beautifully contrived, but only in ^ prospective 
contrivance." 



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WAT^ItRAL THE0LOaY. 319 



CHAPTER XV. 

RELATIONS. 

When s^reral difiereoit parts contrilmte to one 
clEect^ or, whidi is the same thing, when an effect 
is produced by the joint action of differ^it instru- 
ments ; the fitness a£ such parts (»r instruments 
to one another for the purpose of producing, by 
tildr united action, the effect, is what I call 
relation; and wherever this is observed in the 
works of nature or of man it appears to me to 
carry along with it decisive evidence of under- 
4Btanding, intention, Bxt In examining, for in- 
stance, the several parts of a watch, the spring, 
the barrel, the diain, the fosee, the balance, the 
wheels of various sizes, forms, and positions, what 
is it whidi would take an observer's attrition as 
n^st plainly evincing a construction, directed by 
thought, deliberation, and contrivance? It is 
the suitableness of these parts to one another; 
first, in the succession and order in which they 
act; and, secondly, with a view to the effect 
finally produced. Thus, r^erring the spring to 
the wheels, our observer sees in it that whidi 



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320 NATURAL THEOLOGY. 

originates and upholds ^AeiV motion ; in the chain^ 
that which transmits the motion to the fiisee ; in 
the fusee^ that which communicates it to the 
wheels ; in the conical figure of the fiisee^ if he 
refer to the springs he sees that which corrects 
the inequality of its force. Referring the wheels 
to one another^ he notices^ firsts their teethe which 
would have been without use or meaning if there 
had been only one wheel> or if the wheels had had 
no connexion between themselves^ or common 
bearing upon some joint eflTect; secondly, the 
correspondency of their position, so that the teeth 
of one wheel catch into the teeth of another; 
thirdly, the proportion observed in the number 
of teeth in each wheel, which determines the rate 
of going. Beferring the balance to the rest of 
the works, he saw, when he came to understand 
its action, that which rendered their motions 
equable. Lastly, in looking upon the index and 
face of the watch, he saw the use and conclusion 
. of the mechanism, viz. marking the succession of 
minutes and hours ; but all depending upon the 
motions within, all upon the system of interme- 
diate actions between the spring and the pointer. 
What thus struck his attention in the several 
parts of the watch he might probably designate 
by one general name of "relation; " and observ- 
ing with respect to all cases whatever, in which 



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NATURAL THEOLOGT. 321 

the origin and formation of a thing could be 
ascertained by evidence^ that these relations were 
foimd in things produced by art and design^ and 
in no other things, he would rightly deem of 
them as characteristic of such productions. To 
apply the reasoning here described to the works 
of nature. 

The animal oeconomy is fvJl, is made up, of 
these relations, 

I. There are, first, what in one form or other 
belong to all animals, the parts and powers which 
successively act upon their food. Compare this 
action with the process of a manufactory. In 
men and quadrupeds the aliment is first broken 
and bruised by mechanical instruments of masti- 
cation, viz. sharp spikes or hard knobs, pressing 
against or rubbing upon one another ; thus ground 
and comminuted it is carried by a pipe into the 
stomach, where it waits to undergo a great chy- 
mical action, which we call digestion: when di- 
gested it is delivered through an orifice, which 
opens and shuts, as there is occasion^ into the 
first intestine ; there, after being mixed with cer- 
tain proper ingredients, poured through a hole in 
the side of the vessel, it is farther dissolved: in 
this state the milk, chyle, or part which is wanted, 
and which is suited for animal nourishment, is 
strained off by the mouths of very small tubes 

p3 



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322 HATUKAL THBOLOaT* 

Opening into the <eaTity of the intestines ; thtn 
freed from its groiser parts> the pereolated fluid 
it earned by a long, winding, but traceable course, 
into the main stream of the old circulation ; which 
conveys it in its progress to every part of tte 
body. Now I say again, compare this with the 
process of a manufactory, with the making of 
cider, for example; with the bruising of the 
apples in the mill, the squeezing of them when 
so bruised in the press, the fermentation in the 
vat, the bestowing of the liquor thus fermented in 
the hogsheads, the drawing off into bottles, the 
pouring out for use into the glass. Let any one 
diow me any difference betweai these two cases 
as to the point of contrivance. That which is at 
present under our consideration, the '' relation *' 
of the parts successively employed, is not more 
clear in the last case than in the first. The apt- 
ness of the jaws and teeth to prepare the food for 
the stomach is, at least, as manifest as that of the 
cider-miU to crush the apples for the press. The 
concoction of the food in the stomach is as neces- 
sary for its future use as the fermentation of the 
stum in the vat is to the perfection of the liquor. 
The disposal of the aliment afterwards, the action 
and change which it undergoes, the route which 
it is made to take, in order that, and until that, 
it arrive at its destination, is more complex indeed 



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NATURAL THBQIXOY. 323 

intricate^ but» in tke midst dT complicatiQsi 
and intricacy, as evident and certain as is the apr 
paiatus of <»)cks, pipes^ tunnels, for transferring 
tibe cider from, one vessd to another ; of barrdft 
jffld bottles fOT preserving it till fit for use, or of 
cups and glasses for bringing it when wanted to 
the lip of the consumer. The character of the 
machinery is in both cases this, — that one part 
answers to another part, and every part to the 
final result. 

This parallel between the alimentary operation 
and some of the processes of art might be carried 
farther into detail. Spallanzani has remarked* 
a circumstantial resemblance between the sto- 
machs of gallinaceous fowls and the structure o£ 
eorn-mills. Whilst the two sides of the gizzard 
perform the office of the miU-stones, the craw or 
crop supplies the place of the hopper. 

When our fowls are abundantly supplied with 
meat, they soon fill their craw ; but it does not 
immediately pass thence into the gizzard; it 
always enters in very small quantities, in propor- 
tion to the progress of trituration, in like manner 
as, in a mill, a receiver is fixed above the two 
large stones which serve for grinding the corn, 
which receiver, although the com be put into it 
in bushels, allows the grain to dribble only in 

* Disc. i. sec. liv. 



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324 NATURAL THBCnUOOT. 

small quantities into the central hole in the upper 
mill-stone. 

But we have not done with the alunentaxy his- 
tory. There subsists a general relation between 
the external organs of an animal by which it 
procures its food and the internal powers by which 
it digests it. Birds of prey, by their talons and 
beaks, are qualified to seize and devour many 
species both of other birds and of quadrupeds. 
The constitution of the stomach agrees exactly 
with the form of the members. The gastric juice 
of a bird of prey, of an owl, a fakon, or a kite, 
acts upon the animal fibre alone ; it will not act 
upon seeds or grasses at all. On the other hand, 
the conformation of the mouth of the sheep or the 
ox is suited for browsing upon herbage. Nothing 
about these animals is fitted for the pursuit of 
living prey. Accordingly it has been found by 
experiments, tried not many years ago, with per- 
forated balls, that the gastric juice of ruminating 
animals, such as the sheep and the ox, speedily 
dissolves vegetables, but makes no impressicm 
upon animal bodies. This accordancy is still more 
particular. The gastric juice, even of grani- 
vorous birds will not act upon the grain whilst 
whole and entire. In performing the experiment 
of digesting with the gastric juice in vessels, the 
gain must be crushed and bruised before it be 



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NATURAL THEOLOGY. 325 

submitted to the menstruum^ that is to say^ must 
undergo by art, without the body, the preparatory 
action which the gizzard exerts upon it within the 
body, or no digestion will take place. So strict, 
in this case, is the relation between the offices 
assigned to the digestive organ, between the me- 
chanical operation and the chemical process. 

II. The relation of the kidneys to the bladder, 
and of the ureters to both, i. e., of the secreting 
organ to the vessel receiving the secreted liquor, 
and the pipe laid from one to the other for the 
purpose of conveying it from one to the other, is 
as manifest as it is amongst the diflFerent vessels 
employed in a distillery, or in the communications 
between them. The animal structure, in this 
case, being simple, and the parts easily separated, 
it forms an instance of correlation which may be 
presented by dissection to every eye, or which, 
indeed, without dissection, is capable of being 
apprehended by every understanding. This cor- 
relation of instruments to one another fixes inten- 
tion somewhere. Especially when every other 
solution is negatived by the conformation. If 
the bladder had been merely an expansion of the 
ureter, produced by retention of the fluid, there 
ought to have been a bladder for each ureter. 
One receptacle fed by two pipes issuing from 
different sides of the body, yet from both con- 



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326 KAT0RAL TUXQLOOnr. 

f mjm g ike Bmaoe fuid, k not to be acoonalod for 
by any such svppositioii as tbis. 

III. Belatkm of parts to oee another aecompa- 
nies us throughout the wh<de auhnal economy. 
Can any rdatvHi be more simple, yet more con- 
mciiig titan tiiis, that the eyes are so ^aced aa 
to look in the direction in whidi the legs move 
and the hands work? It might hare happened 
very differently if it 1^ been left to chance. 
There wete at least three quartos of the compass 
out of four to have erred in. Any considerate 
alteration in the position of the eye or the 
figure of the joints would have disturbed the line, 
and destroyed the alliance between the sense and 
the limbs. 

IV. But relation, perhaps, is nerer so striking 
as when it subsists, not betwe^i difierent parts of 
the same thing, but between diffinsnt things. 
The relation between a lock and a key is more 
obvious than it is between diflRerent parts of the 
lock. A bow was designed for an arrow, and an 
arrow for a bow ; and the design is more evident 
for their being separate implements. 

Nor do the works of the Deity vwmt tins clearest 
species of relation. The sexes are manifestly made 
for each other. They form the grand relation of 
animated nature, universal, organic, mechanical, 
subsisting, like the clearest relations of art, in 



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dyfierent iittimdiidys, 'm^iiiYoeal, i&es^piicuibfe 
witliout design. 

So mudi AO^ tJiat,w^eEe«veryotiier proof of ecm- 
triraiice in naUire dubious or obscure this ahme 
proald be sufficient. Tbe exainple is complete. 
'Notbing is wantmg to the as^gum^at. I see no 
way -whatever of getting over it. 

y . The teats of animals which gpiye suck^ bear 
a rdation to the mouth of the suckling progeny^ 
particularly to the lips and tongue. Here also> 
as before, is a correspondency of parts^ which parts 
subsist in different individuals. 

Tha^ are general relations^ or the. relations of 
parts which are found either in all animals or in 
large classes and descriptions of animals. Parti- 
eular relations, or the relations which subsist be- 
tween the particular configuration of one or more 
parts of certain species of animals, and the parti- 
eular configuration of erne or more other parts of 
the same animal (which is the sort of relation 
that is, perhaps, most striking) are such as the 
fdlowing : 

I. In the swan, the web-foot, the ^^>oon-bill, the 
long neck, the thick down, the graminivorous sto- 
mach, bear all a relation to one another, inasmuch 
.as they all concur in one design, that of supplying 
the occasions of an aquatic fowl floating upon the 



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328 NATURAL THB(X.0OT« 

sarface of shallaw pools <^ water^ and seeking its 
food at the bottom. Begin with any one of thescr 
particularities of structure^ and observe how the 
rest follow it. The web-foot qualifies the bird 
for swimming ; the spoon-bill enables it to grase. 
But how is an animal floating upon the surface of 
pools of water to graze at the bottom^ except by 
the mediation of a long neck? A long neck 
accordingly is given to it. Again^ a warm- 
blooded animal which was to pass its life upon 
water> required a defence against the coldness oi 
that element. Such a defence is fiimished to the 
swan in the muff in which its body is wrapped. 
But all this outward apparatus would have been 
in vain^ if the intestinal system had not been 
suited to the digestion of vegetable substances. 
I say suited to the digestion of vegetable sub- 
stances; for it is well known that there are two 
intestinal systems found in birds: one with a 
membranous stomach and a gastric juice^ capable 
of dissolving animal substances alone — the other ' 
with a crop and gizzard calculated for the moist- 
ening, bruising, and afterwards digesting, of vege- 
table aliment. 

Or set off with any other distinctive part in the 
body of the swan; for instance, with the long 
neck. The long neck, without the web-foot, 
would have been an encumbrance to the bird; 



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NATURAL THEOLOGY. 329 

yet there is no necessary connexion between a 
long neck and a web-foot. In fact they do not 
usually go together. How happens it, therefore, 
that they meet only when a particular design de- 
mands the aid of both ? 

II. This mutual relation, arising from a sub- 
serviency to a common purpose, is very observable 
also in the parts of a mole. The strong short 
legs of that animal, the palmated feet, armed 
with sharp nails, the pig-like nose, the teeth, the 
velvet coat, the small external ear, the sagacious 
smell, the sunk protected eye, all conduce to the 
utilities or to the safety of its under-ground life. 
It is a special purpose, specially consulted through* 
out. The form of the feet fixes the character of 
the animal. They are so many shovels; they 
determine its action to that of rooting in the 
ground; and everything about its body agrees 
with this destination. The cylindrical figure of 
the mole, as. well as the compactness of its form, 
arising from the terseness of its limbs, propor- 
tionably lessens its labour ; because, according to 
its bulk, it thereby requires the least possible 
quantity of earth to be removed for its progress. 
It has nearly the same structure of the face and 
jaws as a swine, and the same ofiice for them. 
The nose is sharp, slender, tendinous, strong, 
with a pair of nerves going down to the end of it. 



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SIO KATURAL TUSOU>OT. 

The plftrii 'Covering nrhieh, by the wawi^knGm, 
efefieness^ and polish of tlie short piks that oom? 
poee it, rejects the adhesion of almost every spe* 
oies of earth, defends the animal from eoM aad 
wet, and from the impediment whidi st would ex* 
perience by the mould sticking to its body. 
From soils of all kinds the little pioneer comes 
forth bright and clean. Inhabiting dirt, it is <tf 
all animals the neatest 

But what I have always most admbri in the 
nnde is its eyes. This animal occasionally visiting 
the surfftce, and wanting, for its safety and direc- 
tion, to be informed when it does so, or when it 
approaches it, a perception of light was necessary. 
I do not know that the clearness of sight depends 
at all upon the size of the organ. What is gained 
by the larg^iess or prominence of the globe of 
the eye, is width in the fidd of vi^m. Such a 
capacity would be of no use to an animal wlndi 
was to seek its food in the dark. The mole did 
«ot want to look About it; nor wcMild a large 
advanced eye have been easily d^nded from tJie 
annoyance to which the Hfe of the animal most 
constantly expose it. How indeed was the mote, 
working its way under ground, to guard its eyes 
at all ? In order to meet this difficulty, the eyes 
are made scarcely larger than the head of a 
tXHrking-pin ; and these minute globules are sunk 



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KATOBAL THBOIiOaT. 331 

•o deeply in Hie dkull^ aad lie 00 sluitered ^^tUm 
tbe Telret of its c^^ermg, as tiuct «ny eoatcaetkn 
«f ^at may l)e called ibeeye-bro(«s, .not ^bIj 
'dcMses %^ the apertttres nvbkli lead to ihe eytM, 
imt preaeiitiB a.ecisiuMBi^ as it mem, taany sharp or 
pmtrudtag aubsta&ce wiiioh night ^udi agamat 
tkem. This aperture, even in its oiidinaxy statu^ 
is like a pin-hole in a piece of velvet, scarcely per- 
vious to loose particles of earth. 

Observe, then, in this structure, that which we 
call relation. There is no natural connexion 
between a small sunk eye and a shovel palmated 
foot. Palmated feet might have been joined 
with goggle eyes ; or small eyes might have been 
joined with feet of any other form. What was it 
therefore which brought them together in the 
mole ? That which brought together the barrel, 
the chain, and the fusee in a watch — design ; and 
design in both cases inferred, from the relation 
which the parts bear to one another in the prose- 
cution of a common purpose. As hath already 
been observed, there are different ways of stating 
the relation, according as we sat out from a dif- 
ferent part. In the instance before us, we may 
either consider the shape of the feet, as qualifying 
the animal for that mode of life and inhabitation 
to which the structure of its eyes confines it; or 
we may consider the structure of the eye as the 



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332 NATURAL THBOLOQT. 

only one which would have suited with the action 
to which the feet are adapted. The relation is 
manifest^ whichever of the parts related we place 
first in the order of our consideration. In a word^ 
the feet of the mole are made for digging : the 
neck^ nose^ eyes> ears^ and skin^ are peculiarly 
adapted to an underground life ; and thia is what 
I call relation. 



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NATURAL THEOLOGY. 333 



CHAPTER XVI. 

COMPENSATION. 

Compensation is a species of relation. It is rela- 
tion when the defects of one part^ or of one organ^ 
are supplied by the structure of another part, or 
of another organ. Thus — 

I. The short unbendmg neck of the elephant 
is compensated by the length and flexibility of his 
proboscis. He could not have reached the ground 
without it ; or, if it be supposed that he might 
have fed upon the fruit, leaves, or branches of 
trees, how was he to drink ? Should it be asked, 
why is the elephant's neck so short ? it may be 
answered, that the weight of a head so heavy could 
not have been supported at the end of a longer 
leaver. To a form, therefore, in some respects 
necessary, but in some respects also inadequate to 
the occasion of the animal, a supplement is added, 
which exactly makes up the deficiency under which 
he laboured. 

If it be suggested that this proboscis may have 
been produced, in a long course of generations, by 
the constant endeavour of the elephant to thrust 
out its nose (which is the general hypothesis by 



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334 NATUHAI. TWBOhOat. 

which it has lately been attempted to account for 
the forms of animated nature)^ I would ask^ How 
was the animal to subsist in the mean time — 
during the process — uaM this prolongation of 
snout were completed? What was to become of 
the individual whilst the species was perfecting ?•* 

^ Whilst we haye before us the daily proof of t1» 
capacities of animals for domestication, in considering 
their structure [and their instincts, we must look back 
into that long period before man's creation, when they 
had not his protection and care. A thousand concurring 
testimonies prove that there were periods when the 
earth's surface was more suitable for brutes than it was 
for the abode of man; and when they were grouped 
together, each species with its enemy, and each widi a 
power of preservation, at once to prevent too great aa 
increase and total extermination. The young hont^ 
which in his paddock has neither known bad treatniei^ 
nor an enemy, will yet shiver and start away from a 
brindled swine, or any animal that is bristled or rou^ 

Geological researches, so happily combined with em^ 
parative anatomy, give us no room to conjecture that 
there has been anything like a progressive improve- 
ment in the species of animals. They have been created 
with all the characters in which they are now propa- 
gated ; and had it been otherwise, the species would have 
become extinct, or they would have lost their place in 
that balance of offence and defence by which it has 
pleased the Creator to pnmde for their continuance. 



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If ▲TUBAL THEOLOGY. 935 

Otor business at pres^it is, simply to pcnni o«^ 
the relation which tliis organ bears to the peculiar 
figure of the animal to which it be^longs* And 
herein all things correspond. The necessity of 
the elephant's J^oboseis arises from the shortness 
of hk neck : the shortness of the neck is rendered 
necessary by the weight of the head. Were w0 
to enter into an examination of the structure and 
anatomy of the proboscis itself, we should see im 
it one g( the most curious of all examples of ani- 
mal mechanism. The disposition of the ringlets 
and fibres, for the purpose, first, of forming a 
long cartilaginous pipe ; secondly, of contracting 
and lengthening that pipe ; thirdly, of turning it 
in every direction at the will of the luiimal; with 
the superaddition at the end, of a fleshy produce 
tion, of about the length and thidcness of a finger. 

One would imagine that an idea so wild, as that an 
animal should produce the variety of organs or external 
instruments which we see, by an effort— an energy pro- 
ceeding from itself, could never have been maintained in 
an age like the present, when it is so fully proved that 
there is no change upon the extremity of an animal, no 
additional organ like this of the trunk of an elephant, no 
variety in its paw or its hoof, but what is attended with 
a corresponding alteration in the whole system of the 
creature— of its bones, its teeth, its stomach, as well as 
in its appetites and desires. 



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336 NATURAL THEOLOGY. 

and performing the office of a finger, so as to pick 
up a straw from the ground. These properties 
of the same organ, taken together, exhibit a spe- 
cimen, not only of design (which is attested by 
the advantage), but of consummc(te art, and, as I 
may say, of elaborate preparation, in accomplish- 
ing that design. 

II. The hook in the wing of a bat is strictly a 
mechanical, and, also, a compensating contrivance. 
At the angle of its wing there is a bent claw, 
exactly in the form of a hook, by which the bat 
attaches itself to the sides of rocks, caves, and 
buildings, laying hold of crevices, joinings, chinks, 
and roughnesses. It hooks itself by this claw; 
remains suspended by this hold; takes its flight 
from this position : which operations compensate 
for the decrepitude of its legps and feet. Without 
her hook, the bat would be the most helpless of 
all animals. She can neither run upon her feet, 
nor raise herself from the ground. These inabili- 
ties are made up to her by the contrivance in her 
wing; and in placing a claw on that part, the 
Creator has deviated from the analogy observed 
in winged animals. A singular defect required a 
singular substitute. 

III. The crane-kind are to live and seek their 
food amongst the waters ; yet, having no web- foot, 
are incapable of swimming. To make up for this 



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NATURAL THEOLOGY. 337 

deficiency, they are furnished with long legs tot 
wading, or long bills for groping, or usually with 
both. This is compensation. But I think the 
true reflection upon the present instance is, how 
every part of nature is tenanted by appropriate 
inhabitants. Not only is the surface of deep 
waters peopled by numerous tribes of birds that 
swim, but marshes and shallow pools are fur- 
nished with hardly less numerous tribes of birds 
that wade. 

IV. The common parrot has, in the structure 
of its beak, both an inconveniency and a compen- 
sation for it. When I speak of an inconveniency 
I have a view to a dilemma which frequently 
occurs in the works of nature — viz., that the pe- 
culiarity of structure by which an organ is made 
to answer one purpose necessarily unfits it for 
some other purpose. This is the case before us. 
The upper bill of the parrot is so much hooked, 
and so much overlaps the lower, that if, as in 
other birds, the lower chap alone had motion, the 
bird could scarcely gape wide enough to receive 
its food : yet this hook and overlapping of the 
bill could not be spared, for it forms the very 
instrument by which the bird climbs, — to say 
nothing of the use which it makes of it in break- 
ing nuts and the hard substances upon which it 
feeds. How, therefore, has nature provided for 

Q 



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338 NATURAL THEOLOGY. 

tiie opening of iMs occloded mouth ? By making 
tke upper diap mopi^eable, as i;«iell as the lower. In 
most birds^ the upper chap is connected, and 
makes bat one piece^ with the skull ; but in the 
parrot the upper chap is joined to the bone of the 
head by a strong membrane placed on each side 
of it, which lifts and depresses it at pleasure.* 
V. The spider's web is a compensating contriv- 




ance. The spider lives upon flies, without wings 
to pursue them, — a case, one would have thought, 
of great difficulty, yet provided for, and provided 
for by a resource which no stratagem, no eSort of 
• fioldsmiih^ Nat. Hist. toL v. p. 274. 



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NATURAL THEOLOGY. 839 

the animal, could have produced, had not both its 
external and internal structure been specifically 
adapted to the operation**. 

** There are .few things better suited to remove the 
disgust into which young people are betrayed on the 
view of some natural objects, than this of the spider. 
They will find that the most despised creature may be- 
come a subject of admiration, and be selected by the 
naturalist to exhibit the marvellous works of the creation. 
The terms given to these insects lead us to expect inter- 
esting particulars concerning them, since they have 
been divided into vagrants, himters, swimmers, and 
water- spiders, sedentary, and mason -spiders ; thus 
evincing a variety in their condition, activity, and 
mode of life ; and we cannot be surprised to find them 
varying in the performance of their vital functions (as, 
for example, in their mode of breathing), as well as in 
their extremities and instruments. Of these instruments 
the most striking is the apparatus for spinning and weav- 
ing, by which they not only fabricate webs to entangle 
their prey, but form cells for their residence and con- 
cealment; sometimes hving in the ground, sometimes 
under water, yet breathing the atmosphere. Corre- 
sponding with their very singular oiganization are their 
instincts. We are familiar with the watdifiiln^s and 
voracity of some spiders, when their prey is indicated by 
the vibration of like cords of their net-work. Others have 
the eye $nd disposition of the lynx or t^ar, and a£ter 

q2 



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340 NATURAL THEOLOGY. 

VI. In many species of insects the eye is fixed, 
and consequently without the power of turning* 

couching in concealment, leap upon their victims. Some 
conceal themselves under a silken hood or tube, six eyes 
only projecting. Some bore a hole in the earth, and 
line it as finely as if it were done with the trowel and 
mortar, and then hang it vnth deHcate curtains. A very 
extraordinary degree of contrivance is exhibited in the 
trap-door spider. This door, from which it derives its 
name, has a frame and hinge on the mouth of the cell, and 
is so provided that the claw of the spider can lay hold 
of it, and whether she enters or goes out, says Mr. Kirby, 
the door shuts of itself But the water-spider has a do- 
micile more curious still : it is under water, with an 
opening at the lower part for her exit and entrance ; and 
although this cell be under water, it contains air like a 
diving-bell, so that the spider breathes the atmosphere. 
The air is renewed in the cell in a manner not easily ex- 
plained. The spider comes to the surface; a bubble of 
air is attracted to its body ; with this air she descends, and 
gets under her cell, when the air is disengaged and rises 
into the cell ; and thus, though under water, she lives in 
the air. There must be some peculiar property of the 
surface of this creature by which she can move in the 
water surrounded with an atmosphere, and live under the 
water breathing the air. 

The chief instrument by which the spider performs 
these wonders is the spinning apparatus. The matter 
from which the threads are spun is a liquid contained in 



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NATURAL THEOLOGY. 341 

the pupil to the object. This great defect is, how- 
ever, perfectly compensated, and by a mechanism 
which we should not suspect. The eye is a mul- 
tiplying-glass with a lens looking in every direc- 
tion and catching every object. By which means, 
although the orb of the eye be stationary, the 
field of vision is as ample as that of other animals, 
and is commanded on every side. When this 
lattice-work was first observed, the multiplicity 
and minuteness of the surfaces must have added 
to the surprise of the discovery. Adams tells us 
that fourteen hundred of these reticulations have 
been counted in the two eyes of a drone-bee. 
In other cases the compensation is effected by 

cells ; the ducts from these cells open upon little pro- 
jecting teats, and the atmosphere has so immediate an 
effect upon this liquid, that upon exposure to it, the se- 
cretion becomes a tough and strong thread. Twenty- 
four of these fine strands form together a thread of the 
thickness of that of the silk-worm. We are assured that 
there are three different sorts of material thus produced, 
which are indeed required for the various purposes to 
which they are applied — as, for example, to mix up with 
the earth to form the cells, — to line these cells as with 
fine cotton, — to make light and floating threads by which 
they may be conveyed through the air, as well as those 
meshes which are so geometrically and correctly formed 
to entrap their prey. 



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342 NATURAL THEOLOGY. 

the number and position of the eyes themselves; 
The spider has eight eyes, mounted upon different 
parts of the head; two in front, two in the top of 
the head, two on each side. These eyes are wilii- 
out motion, but, by their situation, suited to com- 
prehend every view which the wants or safety of 
the animal rendered it necessary for it to take. 

VII. The Memoirs for the Natural History of 
Animals, published by the French Academy, 
A. D. 1687, famish us with some curious particu- 
lars in the eye of a cameleon. Instead of two 
eyelids, it is covered by an eyelid with a hole in 
it. This singular structure appears to be cttm- 
pensafory, and to answer to some other singulari- 
ties in the shape of the animal. The neck of the 
cameleon is inflexible. To make up for this, the 
eye is so prominent as that more than half of 
the ball stands out of the head, by means of which 
extraordinary projection the pupil of the eye can 
be carried by the muscles in every direction, and 
is capable of being pointed towards every objecL 
But then, so unusual an exposure of the globe q£ 
the eye requires for its lubricity and defence a 
more than ordinary protection of eyelid, as well as 
a more th^m ordinary supply of moisture; yet ih& 
motion of an eyelid, formed according to the com^ 
mon construction, would be impeded, as it shouM 
seem, by the convexity of the organ. The aper- 



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NATURAL THEOLOGT. 343 

ture in the lid meets this difficulty. It eiuibleB 
the animal to keep the principal part of the sur- 
face of the eye under cover, and to preserre it in 
a due state of humidity without shutting out the 
light, or without performing every moment a nio- 
titatien which it is probable would be more labo- 
rious to this animal than to others. 

VIII. In another animal, and in ai^ther part 
of the animal economy, the same Memoirs describe 
a most remarkable substitutioru The reader will 
remember what we have already observed coifr- 
ceming the iniestiiial canal*— that its length, so 
many times exceeding that of the body, promotes 
the extraction of the chyle from the aliment by 
giving room for the lacteal vesseb to act upon it 
through* a greater space. This long intestine, 
wherever it occurs, is in other animals disposed in 
the abdomen from side to side in returning folds. 
But in the adiimaL now under our notice tke mat- 
ter is managed otherwise. The same intention is 
mechanically effectuated, but by a mechanism of 
a different kind. The animal of wlucb I speak is 
an amphibious quadruped, which our authors caU 
the alopecias or sea^fox. The intestine ia strai^t 
from one end to the other ; but in this straight 
and consequently short intestine is a winding, 
corkscrew, spiral passage, through whick the food^ 
not without several circumvolutions, and in fact 



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344 NATURAL THEOLOGY. 

by a long route, is conducted to its exit. Here 
the shortness of the gut is compensated by the ob- 
liquity of the perforation. 

IX. But the works of the Deity are known by 
expedients. Where we should look for absolute 
destitution — where we can reckon up nothing but 
wants — some contrivance always comes in to sup- 
ply the privation. A snail, without wings, feet, 
or thread, climbs up the stalks of plants by the 
sole aid of a viscid humour discharged from her 
skin. She adheres to the stems, leaves, and fruits 
of plants by means of a sticking-plaster. A 
mtissel, which might seem by its helplessness to 
lie at the mercy of every wave that went over it, 
has the singular power of spinning strong ten- 
dinous threads by which she moors her shell to 
rocks and timbers. A cockle, on the contrary, 
by means of its stiff tongue, works for itself a 
shelter in the sand. The provisions of nature 
extend to cases the most desperate. A lobster 
has in its constitution a difficulty so great that 
one could hardly conjecture beforehand how na- 
ture would dispose of it. In most animals the 
skin grows with their growth. If, instead of a 
soft skin, there be a shell, still it admits of a gra- 
dual enlargement. If the shell, as in the tortoise, 
consist of several pieces, the accession of substance 
is made at the sutures. Bivalve shells grow 



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NATURAL THEOLOGY. 345 

bigger by receiving an accretion at their edge ; 
it is the same with spiral shells at their mouth. 
The simplicity of their form admits of this. But 
the lobster's shell being applied to the limbs of 
the body, as well as to the body itself, allows not 
of either of the modes of growth which are ob- 
served to take place in other shells. Its hard- 
ness resists expansion ; and its complexity renders 
it incapable of increasing its size by addition of 
substance to its edge. How then was the growth 
of the lobster to be provided for ? Was room to 
be made for it in the old shell, or was it to be 
successively fitted with new ones ? If a change 
of shell became necessary, how was the lobster to 
extricate himself 'from his present confinement? 
how was he to uncase his buckler, or draw his 
legs out of his boots ? The process which fisher- 
meii have observed to take place is as follows. 
At certain seasons the shell of the lobster grows 
soft ; the animal swells its body ; the seams open, 
and the claws burst at the joints. When the shell 
has thus become loose upon the body, the animal 
makes a second effort, and by a tremulous spas- 
modic motion casts it off. In this state the libe- 
rated but defenceless fish retires into holes in the 
rock. The released body now suddenly pushes 
its growth. In about eight-and-forty hours a 
fresh concretion of h\miour upon the surface, i. e,, 

Q 3 



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346 NATURAL THEOLOOT. 

8 new shell, is formed, adapted hi every paart to 
the increased dimensions of the animah Tfans 
wonderful mutation is repeated erery year^. 

If there be imputed defects without compensar 
tion, I should suspect that they were defects only 
in appearance. Thus, the l)ody of the doHi has 
often been reproached for the slowness of its mo- 
tions, which has been attributed to as imperfect 
tion in the formation of its limbs. But it ought 
to be observed that it is this slowness whidi aloae 
suspends the voracity of the animai:. He &stfi 
during his migration from one tree to a^^Aer: 
and this fast may be necessary for the veKef of hk 
overcharged vessels, as well as to aUow lime fcr 
the concoction of the mas» of coarse and hasd 
food which he has taken into his stomach. Tke 
tanfiness of his pace seems to have reference to 
the capacity of his organs, and to his propensiAicB 
with respect to food — i, e., is ealcidated to coun- 
teract the effects of repleticm. 

Or there may be cases in which a defect is 
artificial, and compensated by the very eaose 
which produces it. Thus the sheep, in tiie domffii- 
ticated state in which we see it, i» destitute of tiie 
ordinary means of defence or escape — is ineapaUbe 
either of resistance or ffight. But this is not so 

•• See Appendix. 



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NATURAL THEOLOeT. 3£7 

wi A the wild animaL The natural sheep is swift 
and active ; and^ if it lose these qualities when it 
comes under the subjection of man> the loss is 
compensated- by his protection. Periiaps thore is 
n0 species of quadruped whatever whidi suflesa so 
little as this does from the depredation of airimafe 
of prey. 

For the sake o£ moldng our meaning better 
understood, we have considered thia business of 
compensation under certain pa/rticiUcmtiea of con- 
stitution in which it appears to be most conspir 
cuous. This view of the subject necessarily limits 
Hie instances to single species of animals. But 
there are compensations, perii^s not less cai4un, 
which extend over large classes and to large pos- 
tions of living nature. 

L In quadrupeds, the deficiency of teetL is 
usually compensated by the hexdtj oi ruminadaa. 
The sheep, deer, and ox tribe are without fore- 
teeth in the upper jaw^. These ruminate. The 
horse and ass are &mished with teeth in the 
upper jaw, and do not ruminate. In the former 
class, the grass and hay descend into the stomach 
nearly in the state in which they are cropped firom 
the pasture or gathered from the bundle. In the 
stomach they are softened by the gastric juice, 

^ See the account of the teeth, in the Appendix. 



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348 NATURAL THEOLOGY. 

which in these animals is unusually copious : thus 
softened and rendered tender, they are returned a 
second time to the action of the mouth, where the 
grinding teeth complete at their leisure the tri- 
turation which is necessary, but which was before 
left imperfect : I say the trituration which is ne- 
cessary; for it appears from experiments that 
the gastric fluid of sheep, for example, has no 
effect in digesting plants unless they have been 
previously masticated; that it only produces a 
slight maceration, nearly as common water would 
do in a like degree of heat ; but that when once 
vegetables are reduced to pieces by mastication, 
the fluid then exerts upon them its specific ope- 
ration. Its first effect is to soften them, and to 
destroy their natural consistency : it then goes on 
to dissolve them, not sparing even the toughest 
parts, such as the nerves of the leaves*. 

I think it very probable that the gratification 
also of the animal is renewed and prolonged by 
this faculty. Sheep, deer, and oxen appear to be 
in a state of enjoyment whilst they are chewing 
the cud : it is then, perhaps, that they best relish 
their food**. 

•* Wherever a seed can lodge we find vegetables 
growing ; and wherever we find digestible matter there 

* Spall. Dis. iii. sect. cxl. 



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NATURAL THEOLOGT. ' 349 

n. In birds, the compensation is still more 
striking. They have no teeth at all. What have 

are animals to live upon it ; and the kind of food deter- 
mines the organization of the creature, not resulting 
from it, but provided for it. The class of ruminants 
feed on the coarser herbage where the vegetable is in 
abundance, but the actual nutritious matter is small in 
quantity compared with the mass. There is therefore 
an obvious necessity for a more complex apparatus to 
extract the smaller proportion of matter capable of being 
animalized : hence the maceration in the first stomach, 
hence the regurgitation and rumination, and the recep- 
tion into the second and third stomachy in preparation 
for the proper digestion in the last. When the mass is 
digested, the nutritious part is still small in proportion 
to the whole ; and to permit that smaller portion of ali- 
ment to be absorbed and carried into the system, the 
intestinal canal must be long and complex, offering re- 
sistance to the rapid descent of the food, and giving it 
lodgment : and thus there is always a correspondence 
between the complication of the stomach and the length 
of the intestines, and between both and the nature of 
the food. It is further very remarkable, that when ani- 
mals of the same species live in different climates, where 
there is more or less abundance of vegetable food, there 
is an adaptation of their digestive organs. Where it is 
abimdant, the configuration of the intestines which is 
intended to delay its descent is less complex. Where 
the food is more scarce, the intestine is longer, and the 



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350 ITATUBAL TUEOIiOCY. 



Amy Hken to malw* nf for tins severe want? I 
■peak of graniToraas and hg rbi v o ri Hi a bircbr anadi 
as common fowls, turkeys> ducks^ geese^ pigeomr, 
&c. ; for it is concerning these alone that the 
question need be asked. All these are fiimished I 

with a peculiar and most powerM muscle^ called 
the gizzard ; the inner coat of which is fitted up 
with rough plaits^ which^ by a strong fiiction 
against one another^ break and grind the hard . 

aliment as effectually, and by the same mechs^ f 

meal actbn, ae a coffee-mill weuld do. It has 
been proved by the most correet %upenaugalmy i 

tha;t the gastric j«ice of these birds wiU not ope- 
rate upon the entire grain : not eren whe» soil- i 
ened by water or macerated in the crop. There- I 
fore, without a grincRng machine within its bo(fy, 
without the trituration of the gizzard^ a chicken 
would have starved upon a heap of corn. Tet, 
why should a bill and a gizzard go together? i 
why should a gizzard never be found where there j 
are teeth ? 

valvular obstruction greater. This has been observed 
by Sir E. Home, in comparing the cassowary of Java 
with the cassowary of New South Wales, and die Ame- 
rican ostrich with the same bird inhabiting the deserts 
of Africa. The same comparison has been made be- 
tween the Leicestershire sheep and the mountain sheep 
of Sootland. 



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If^lLTURAL TBB0X£>6T. 351 

Nor does tiber gkzaxd bciong-to birdff as such. 

A gizzard: is not fiauad in birds of pi?^ : their 

fe»d requizes net ta be ground dawa in a mSl. 

The eompeitsa^r]r am^trwemce goesr no fartbiex 

tiian tke necessity, ht both dasses of birds, h&w- 

ever, ^e digestire organ wiflmr tbe body bears a 

•tiict aoDd mechanical relation to- the exiejaxal 

Histruments for procuring fijod. The soft meia- 

Inraaeite stomach accompanies a hooted notched 

Iwafc; shx»rt nmacuW legs ; strongs sharp, crooked 

iaioiK^r — ih» cartila^nous atomaeh attends that 

coiiferi!m<!Mii of bill and toes^ whidi restraias the 

brrd to t*e pickings of seeife or the- croppinrg of 

plants* 

^ We have said that it is the object to suppOTt animal 
life^ and to. give the ^oyment of existence; and that 
wherever the means are afforded of converting a mate- 
mL under the processes of digestion and assimilation, 
there animals will be found with an apparatus of di- 
gestion adapted to the food. Nothing certainly can be 
more curious than the vicarious action of the stomach 
and mouth. We see, for example^ that where the bill 
FwUides mastication in the mouth, it is perfonned in 
the stomach; and then muscles are found in the sto- 
mach as powerful as those of the jaws and teeth ; and 
as to the teeth, or what is equivalent to them, we 
may say that they are coDLtinually renewed. In fact^no 
mechanical structure of jaws and teeth could answer the 



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352 NATURAL THEOLOGY. 

III. But to proceed with our campengatums. A 
very numerous and comprehensive tribe of terres- 
trial animals are entirely without feet — ^yet loco- 
motive, and in a very considerable degree swift in 
their motion. How is the want of feet compen- 
sated ? It is done by the disposition of the mus- 
cles and fibres of the trunk. In consequence of 

purposes of nature here : no union of bone and enamel, 
in the tooth could have withstood the attrition of the 
gizzard ; and one of the most beautiful and interesting 
i^pUances of nature is the substitution, through the in- 
stinct of the animal, of small stones of hard texture, 
generally consisting of silex, introduced within the grasp 
and action of this organ. It is a further proof that the 
mastication, if we may use the term, is more perfect in 
the gizzard than where there is the most complex struc- 
ture of teeth, and therefore that it is the means of 
extracting the greater quantity of nutritious matter. 
Accordingly, there are gizzards in most classes of animals. 
They are not only found in birds, but in reptiles. The 
sea-turtle has what is termed a muscular stomach. 
Among fishes, the mullet and the gillaroo trout have mus- 
cular stomachs. The cuttle-fish, the nautilus, and even 
the earth-worm, have a crop and gizzard; and insects, 
according as they live on a leaf or suck the blood, have 
the same difFerence in the internal arrangement of the 
structure for assimilation as that which distinguishes the 
ox from the lion. 



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NATURAE THEOLOGr. 353 

the just collocation and by means of the joint 
action of longitudinal and annular fibres — that is 
to say, of strings and rings — the body and train 
of reptiles are capable of being reciprocally short- 
ened and lengthened, drawn up and stretched 
out. The result of this action is a progressive 
^md in some cases a rapid movement of the whole 
body, in any direction to which the will of the 
animal determines it. The meanest creature is a 
collection of wonders. The play of the rings in 
an earth-worm, as it crawls, the undulatory motion 
propagated along the body, the beards or prickles 
with which the annuli are armed, and which the 
animal can either shut up close to its body, or let 
out to lay hold of the roughness of the surface 
upon which it creeps, and the power arising from 
all these of changing its place and position, 
afford, when compared with the provisions for 
motion in other animals, proofs of new and ap- 
propriate mechanism. Suppose that we had never 
seen an animal move upon the ground without 
feet, and that the problem was : Muscular action, 
i, e.y reciprocal contraction and relaxation being 
given, to describe how such an animal might be 
constructed capable of voluntarily changing place. 
Something, perhaps, like the organization of rep- 
tiles might have been hit upon by the ingenuity 
of an artist ; or might have been exhibited in an 



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364 NATURAL THSOLOGX. 

sutomaton, by the combin«tioiL of opEifiga^ 8[»zal 
wires, and rm^ts ; but to the solution o£ the 
problem would not be denied, snrdy, the praise 
of invention and of suecesirful thought r leaat of 
all conld it ever be questioned whether inteU^ 
gence had been employed about it or not^l 

*• Not unconnected with the subject of the last note 
iiB the progreBsion of animals : and we have none 
better suited for the object of this volume than the eon»- 
sideration of the mfinite variety of the instnnnents of 
motion, firom the blubber that floats like froth upon the 
water, to the eagle or Ihe antelope. The genus medusa 
of linnssus embraces those animals like jelly which float 
in the sea. Some of these, when, taken out of the water, 
will weigh fifty ounces, and, on being dried, not more 
than five or six grains. From this it would appear that 
they must be of the specific gravity of water, and hence 
their peculiar organization and mode of existence ; 
especially it accounts for their mode of progression, if 
it can be called so : since they are in a great mea- 
sure passive, and float and are carried by the wind. 
For this purpose there is a vesicle or bladder filled 
with air, which in some rises above the water, and 
the animal is dragged as we might imagine a balloon 
would be after lighting on the water. The walls of this 
sac are muscular, and the animal, by retaining or foscing 
out the air, can either take advantage of the wind,, and 
is sometimea moved with great velocity, or sink under 



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NATURAL THEOLOGY. ^5 

tflie surface, wid move only with the current. There is 
every reason txy beKeve that the air, which is the prin- 
cipal means of change of place, i& secreted by the animal. 

From^ some of these animals tentacnla hang down into 
the water for seizing their food, and perhaps for directing 
their progress. They have a power of distending them, 
orerecting them by forcing water into their texture, by the 
contraction of vesicles near their base. Varieties of these 
animals hoist a plate or crest out of the water, which has 
a still greater resemblance to a sail. 

We have already noticed the fins of fishes, the wing of 
the bird, and the web-foot of the duck. "The meanest 
creature is, indeed, a collection of wonders." In the 
earth-worm or the caterpillar, the head, or the anterior 
part of the body, is projected (and it is a difficult problem 
to produce extension by contraction) till it touches the 
ground, and slightly adheres to it, when the posterior part 
of the body is drawn forwards. In many worms or cater- 
pillars there are holders discoverable upon minute inspec- 
tion, and their anatomy exhibits a perfect set of muscles 
attached to those exterior rough points, — by which it is 
made evident that each of them is a foot. But nothing 
is more interesting than to see the change of the larva 
to the winged insect, where these muscles and their ap- 
propriate nerves disappear : and new muscles, and new 
nerves, and new energies direct the creature that crept 
an inch in an hour to outstrip, as we have said, 
the fleetest horse or to rise upon the wind ; for those 
who travel by the new rail-roads observe bees to fly 



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356 NATURAL THBOLOOT. 

round them, and therefore to move above sixty miles an 
hoar. The contrasts are the most curious between the 
flight of the bat and the motion of the mole ; the same 
organization being calculated, with slight adaptadon, for 
the atmosphere, and for moving under the earth. We 
might almost give the instance of the perforation of solid 
calcareous rock by the boring moUusca, which, by late 
observations, seems to be accomplished by means of 
the foot. 



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NATURAL THEOLOGY. 357 



CHAPTER XVII. 

THE RELATION OF ANIMATED BODIES TO INANIMATE 
NATURE. 

We have already considered relation, and under 
different views ; but it was the relation of parts 
to parts, of the parts of an animal to other parts 
of the same animal, or of another individual of the 
same species. , 

But the bodies of animals hold, in their con- 
stitution and properties, a close and important 
relation to natures altogether external to their 
own : to inanimate substances, and to the specific 
qualities of these ; e. g., they hold a strict relation 
to the ELEMENTS by which they are surrounded. 

I. Can it be doubted, whether the wings of birds 
bear a relation to air, and the^n* offish to water ? 
They are instruments of motion severally suited 
to the properties of the medium in which the 
motion is to be performed ; which properties are 
different. Was not this difference contemplated 
when the instruments were differently consti- 
tuted? 

II. The structure of the animal ear depends 



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356 NATURAL THEOLOGY. 

for its use not simply upon being surrounded by 
a fluid, but upon the specific nature of that fluid. 
Every fluid would not serve : its particles must 
repel one another; it must form an elastic me- 
dium : for it Is by the successive pulses of such a 
medium that the undulations excited by the sur- 
rounding body are carried to the organ ; that a 
communication is formed between the object and 
the sense; which must be done, before the i&- 
temal machinery of the ear^ subtile as it is, can 
aotataU. 

III. The organs of voice and respiration are» 
no less than the ear^ indebted, for tl^ success of 
their operation, to the peculiar quaUttes of the 
fluid in which the animal is immeised. They^^ 
therefore, as well as the ear, are constituted upon 
tiie supposition of such a fluid, L e., of a fluid with 
fi«ich particular properties, being always present. 
Change the properties of the fluid, and the (»rgan 
cannot act ; change the organ, and the properties 
of the fluid would be lost The structure, thesre- 
£bre, of our organs, and the properties of our 
atmosphere, are made for one another^ Ncnt does 
it alter the relation, whetkor you allege the oi^aai 
to be made &r the element (which seems the mosi 
natural way of considering it), or the element 9M 
prepared for the organ. 

IV. But there is another fluid wkh which we 



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NATURAL THEOLOGY. 3S9 

have to do ; with prqpertieB of its own^ with laws 
of acting, and of being acted upon, totally difie- 
Bent irom those of air and water: and that is 
U^. To this new, this singular dement — to qua- 
lities perfectly peculiar, perfectly distinct and re- 
mote from the qualities of any other substance with 
which we are acquainted — ^an organ is adapted, 
an instrument is correctly adjusted, not less pecu- 
liar amongst the parts of the body, not less sin- 
gular in its form and in the substance of which 
it is composed, not less remote from the materials, 
the model, and the analogy of any other part of 
the animal frame, than the element to which it 
relates is specific amidst the substances wiiih 
which we converse. If this does not prove ap- 
propriation, I desire to know what would prove it. 

Yet the element of light and the organ of vision, 
however related in their oflSco and use, have n« 
connexion whatever in their original. The action 
of Tays of light upon the surfaces of animals has 
no tendency to breei eyes in their heads. The 
sun might shine for ever upon living bodies, with- 
out the smallest approach towards producing the 
Bcnae of mght. On the other hand also, the 
animal eye does not generate or emit light. 

V. Throughout the universe there is a won- 
derful proportioning of one thing to another. The 
size of animals, the human animal especially. 



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360 NATURAL THEOLOGY. 

when considered with respect to other animals, or 
to the plants which grow around him, is such as 
a reg^d to his conveniency would have pointed 
out A giant or a pigmy could not have milked 
goats, reaped com, or mowed grass ; we may add, 
could not have rode a horse, trained a vine, shorn 
a sheep, with the same bodily ease as we do, if at 
all. A pigmy would have been lost amongst 
rushes, or carried off by birds of prey ^. 

It may be mentioned, likewise, that the model 
and the materials of the human body being what 
they are, a much greater bulk would have broken 
down by its own weight. The persons of men 
who much exceed the ordinary stature betray this 
tendency. 

VI. Again (and which includes a vast variety 
of particulars, and those of the greatest impor- 
tance), how close is the suitableness of the earth 
and sea to their several inhabitants ; and of these 
inhabitants to the places of their appointed re- 
sidence ! 

Take the earth as it is ; and consider the cor- 
respondency of the powers of its inhabitants with 
the properties and condition of the soil which 
they tread. Take the inhabitants as they are ; 



^* See the Appendix, on the bones of huge animals. 



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NATURAL THEOLOGY. 361 

and consider the . substances which the earth 
yields for their use. They can scratch its sur- 
face, and its surface supplies all which they want. 
This is the length of their faculties ; and such is 
the constitution of the globe, and their own, that 
this is sufficient for all their occasions. 

AVhen we pass from the earth to the sea, from 
land to water, we pass through a great change : 
but an adequate change accompanies us of animal 
forms and functions, of animal capacities and 
wants ; so that correspondency remains. The earth 
in its nature is very different from the sea, and 
the sea from the earth, but one accords with its 
inhabitants as exactly as the other. 

VII. The last relation of this kind which I 
shall mention is that of sleep to night; and it 
appears to me to be a relation which was ex- 
pressly intended. Two points are manifest, first, 
that the animal frame requires sleep ; secondly, 
that night brings with it a silence and a cessation 
of activity which allows of sleep being taken with- 
out interruption and without loss. Animal exist- 
ence is made up of action and slumber; nature 
has provided a season for each. An animal which 
stood not in need of rest would always live in 
daylight. An animal which, though made for 
action, and delighting in action, must have its 
strength repaired by sleep, meets, by its consti- 



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362 NATURAL THEOLOGY. 

tution, the retitms of day and nigld. In the 
human species, for instance, were the bustle, the 
labour, the motion of life upheld by the constant 
presence of lights sleep could not be enjoyed 
without being disturbed by noise, and mthout 
expense of that time which the eagerness of 
private interest would not contentedly resign. It 
18 happy, therefore, for this part of the creation, 
I mean that it is conformable to the firame and 
wants of their constitution, that nature, by the 
very disposition of her elements, has commanded, 
as it were, and imposed upon them, at moderate 
intervals, a general intermission of their toils, 
their occupations, and pursuits. 

But it is not for man, either solely or princi- 
pally, that night is made. Inferior but less per« 
verted natures taste its solace, and expect its re- 
turn with greater exactness and advantage than 
he does. I have often observed, and never ob- 
served but to admire, the satisfaction, no less 
than the regularity, with which the greatest part 
of the irrational world yield to this soft necessity, 
this grateful vicissitude; how comfortably the 
birds of the air, for example, addi*ess themselves 
to the repose of the evening, with what alertness 
they resume the activity of the day. 

Nor does it disturb our argument to confess 
that certain species of animals are in motion 



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NATURAL THEOLOGY. 363 

during the niglit and at rest in the day. With 
respect even to them, it is still true that there is 
a change of condition in the animal^ and an ex- 
ternal change corresponding with it. There is 
still the relation, though inverted. The fact is 
that the repose of other animals sets these at 
liberty, and invites them to their food or their 
sport. , 

If the relation of sleep to night, and, in some > 
instances, its converse, be real, we cannot reflect 
without amazement upon the extent to which it 
carries us. Day and night are things close to 
us; the change applies immediately to our sen- 
sations ; of all the phenomena of nature, it is the 
most obvious and the most femiliar to our ex- 
perience; but, in its cause, it belongs to the 
great motions which are passing in the heavens. 
Whilst the earth glides round her axle she mi- 
nisters to the alternate necessities of the animals 
dwelling upon her surface, at the same time that 
she obeys the influence of those attractions which 
regulate the order of many thousand worlds. The 
relation, therefore, of sleep to night is the rela- 
tion of the inhabitants of the earth to the rota- 
tion of their globe ; probably it is more, it is a 
relation to the system of which tliat globe is a ; 
part ; and, stiU further, to the congregation of 
systems of which theirs is only one. If this ac- 

r2 



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364 NATURAL THEOLOGY, 

count be true, it connects the meanest individual 
with the universe itself^ — a chicken roosting upon 
its perch with the spheres revolving in the firma- 
ment'*. 



" Nothing is more true than that the strength of the 
hones and the power of the muscles stand in intimate 
relation with the weight of the body, that is also, in rela- 
tion with the attraction of the globe itself. It is no less 
certain that many of the living properties of animals, the 
condition of the nervous system, and the alternation of 
exertion and re]K>se in the muscular system, are related to 
the change of day and night, or to the revolving of our 
planet upon its axis. In man we may see a slight devia- 
tion in his habits and occupations from this correspond- 
ence with the succession of light and darkness ; yet he 
enjoys a return of energy and elasticity of spirits, which 
is followed by weariness and exhaustion ; and health will 
not long continue without yielding to the alternate condi- 
tion of activity and repose. In nothing do we see the 
benevolence of the Creator more than in the continued 
gratification consequent on this arrangement alone, and 
more especially in the brutes. It is not a mere effect of 
light and the freshness of the morning which produces 
the almost universal animation and activity of that time of 
day ; for to many animals the light of day is the signal to 
seek repose ; and that it is not the mere necessity which 
brings animals abroad at night, in order to feed se- 
cluded, or escape their enemies, we know from this, that 



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NATURAL THEOLOGY. 365 

VIII. But if any one object to our representsl- 
tion, that the succession of day and night, or the 

their organs are adapted to the obscurer light, and not their 
organs only but their propensities ; for they are as full of 
activity and enjoyment as the things of day. The his- 
tory of pulmonary and other complaints indicates a cu- 
rious connexion between the functions of the body and 
the revolution of time or alternations of day and night. 

But the most remarkable accommodation of the eco- 
nomy of animals, and of the property of life itself in them, 
regards the changes of the year rather than the diurnal 
change. How much this prevails in the vegetable world 
we have only to look around us fully to comprehend. 
With the diminution of heat vegetation is nipped, the 
ova of insects locked up, and the food of many animals 
withdrawn. Some animals could not be protected by an 
instinct of migration, being without the means of pas- 
sage : the bat could not fly away with the swallow, nor 
the hedgehog and dormouse travel with the deer. To 
sustain the animal heat against the low temperature of 
the surrounding atmosphere requires a vigorous circu- 
lation of the blood and a plentiful and uninterrupted 
supply of food. Many animals must therefore have 
died during the winter had not nature supplied a means 
of their continuance in life beyond the ingenuity of man 
to conceive. The warmth of their clothing, and the 
instincts to build themselves a warm habitation, which 
we should almost say were the exercise of ingenuity, are 



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306 KATITRAL THE0L06T. 

rotation c^ tbe earth upon which it depends^ is 
not resolvable into central attraction, we will refer 
him to that which certainly is, — to the change of 
the seasons. Now the constitution of animals 
susceptible of torpor bears a relation to winter si- 
milar to that which sleep bears to night. Against 
not only the cold, but the want of food, which the 
approach of winter induces, the Preserver of the 
world has provided in many animals by migration, 
in many others by torpor. As one example out 



insufficient. To sustain life they mnst hold it by a new 
tenure. Accordingly the necessity for food is removed ; 
the activity of the circulation is diminished remarkably; a 
torpor seizes upon every living faculty, and they fall into 
what seems a long sleep. Yet it is not sleep, but a new 
condition of existence, in which Hfe is preserved without 
the necessity for food, and when all the functions of the 
system are let down to a lower state of activity. And justly, 
therefore, it has been said that in these things we trace 
the benevolence of the Creator, " who did not cast his 
living creatures into the world to prosper or perish as they 
might find it suited to them or not, but fitted together 
with the nicest skill the world and the constitution which 
he gave to its inhabitants ; so fashioning it, that light 
and darkness, sun and air, moist and dry, should become 
their ministers and benefactors, the unwearied and un- 
failing causes of their well-being." — WheweWs Bridge- 
water Treatise, 



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jf ATURAL theoloqy; 367 

of a thousand^ the bat, if it did not sleep through 
the winter, must have starved ; as the moths and 
flying insects upon which it feeds disappear. But 
the transition from summer to winter carries us 
into the very midst of physical astronomy, that is 
to say, into the midst of those laws which govern 
the solar system at least, and probably all the 
heavenly bodies. 



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368 NATURAL THEOLOGY. 



CHAPTER XVIII. 



INSTINCTS. 



The order may not be very obvious by which I 
place instincts next to relations. But I consider 
them as a species of relation. They contribute, 
along with the animal organization, to a joint 
effect, in which view they are related to that or- 
ganization. In many cases they refer from one 
animal to another animal ; and, when this is the 
case, become strictly relations in a second point of 
^dew. 

An INSTINCT is a propensity prior to experience 
and independent of instruction. We contend 
that it is by instinct that the sexes of animals seek 
each other ; that animals cherish their offspring ; 
that the young quadruped is directed to the teat 
of its dam ; that birds build their nests and brood 
with so much patience upon their eggs; that 
insects which do not sit upon their eggs deposit 
them in those particular situations in which the 
young when hatched find their appropriate food : 
that it is instinct which carries the salmon, and 



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NATURAL THEOLOGY. 369 

some other fish, out of the sea into rivers, for the 
purpose of shedding their spawn in fresh water. 

We may select out of this catalogue the incu- 
bation of eggs. I entertain no doubt but that a 
couple of sparrows hatched in an oven, and kept 
separate from the rest of their species, would 
proceed as other sparrows do in every office which 
related to the production and preservation of their 
brood. Assuming this fact^^ the thing is inexpli- 

^ There can be very little doubt of this assumption 
being according to the fact. Nevertheless, as the ex- 
periment has probably not been actually made, there is 
no harm in mentioning one or two examples of the same 
import, and which are ascertained by repeated observe 
tion. When caterpillars bred upon a tree are shaken 
off and fall for the first time upon the ground, they im- 
mediately regain the tree by crawling up as quick as 
they can. Again — it is a very general law of insects, 
that the grub feeds upon a food which the parent does 
not eat, and yet the latter makes provision for the gTub. 
Thus the solitary wasp deposits its eggs, each in a hole, 
and then collects a certain number of green worms, 
which she rolls up and deposits in the same hole, over 
the egg. When the grub is hatched, it feeds upon these 
worms until transformed into a young wasp. And here 
two things are remarkable : first, the wasp itself never 
feeds upon the worm, or indeed on any animal food; 
and next, M. Reaumur found that she provides jiist 

r5 



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970 lUkTIIBAL TBBOUQOr. 

caUe upon a&jr otliftr hypotkesis than diat <tf ma 
instinct impressed upon tlie oonstikition of tte 
»iMT"ftJ For, first, what should induce the female 
bard to prepare a nest before fihe lays her ^gs ? 
It is in vain to suppose her to be possessed of the 
fiM;i]dty of reasoning ; for no reasoning will reach 
ilie case. The fiilness or distension whidb she 
might fed in a particular part of the body, frcaa 
the growth and solidity of the egg within her, 
could not possibly inform her that she was about 
to produce something which, when produced, was 
to be preserved and taken care of. Prior to 
experience there was nothing to lead to this infer- 
ence, or to this suspicion. The amdogy was all 
against it; for, in every other instance, what 
issued from the body was cast out and rejected. 

But, secondly, let us suppose the egg to be 
produced into day ; how should birds know that 
their eggs contain their young? There is no- 



enough of the worms to sustain the grub till it becomes a 
fly, and changes its food. Our author dwells afterwards 
upon the application to the argument of the fact that the 
parent insect never sees its young. The architecture of 
bees ^affords perhaps the most striking illustration; for 
those which have been taken without evCT having any 
communication with the former race, build precisely in 
tiiic accustomed manner. See the next note. 



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KATltRAL THBOLOGT. 3^71 

thing eitlier in die aspect cr in the internal com' 
posiidon of an egg which could lead even the most 
daring imagination to conjecture that it was here- 
after to turn out from under its shell a living 
perfect bird. The form of the egg bears not the 
rudiments of a resemblance to that of the bird. 
Inspecting its contents^ we find still less rea- 
son, if possible, to look for the result which actu- 
ally takes place. If we should go so far as, from 
the appearance of order and distinction in the 
disposition of the liquid substances which we no- 
ticed in the egg, to guess that it might be de- 
signed for the abode and nutriment of an animal 
(which would be a very bold hypothesis), we 
should expect a tadpole dabbling in the slime^ 
much more than a dry, winged, feathered crea- 
ture, a compound of parts and properties impos- 
sible to be used in a state of confinement in the 
egg, and bearing no conceivable relation, either 
in quality or material, to anything observed in it. 
From the white of an egg, would any one look for 
the feather of a goldfinch ? or expect from a simple 
uniform mucilage the most complicated of all ma- 
chines, the most diversified of all collections of 
substances ? Nor would the process of incuba- 
tion, for some time at least, lead us to suspect the 
event. Who that saw red streaks shooting in the 
fine membrane which divides the white from thje 



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372 NATURAL THEOU)OT, 

- yolk would suppose that these were about to be- 
come bones and limbs? Who that espied two 
discoloured points first making their appearance in 
the cicatrix, would have had the courage to predict 
that these points were to grow into the heart and 
. head of a bird ? It is difficult to strip the mind of 
its experience. It is difficult to resuscitate sur- 
prise when familiarity has once laid the sentiment 
asleep. But could we forget all that we know, 
and which our sparrows never knew, about ovipa- 
rous generation — could we divest oiurselves of 
every information but what we derived from rea- 
soning upon the appearances or quality disco- 
vered in the objects presented to us — I am con- 
vinced that Harlequin coming out of an egg upon 
the stage is not more astonishing to a child than 
the hatching of a chicken both would be, and 
ought to be, to a philosopher ^*. 



^* The manner in which the chicken breaks the eg^ is 
one of the most wonderful operations of instinct, and is a 
process marked by the uniformity of instincts. For as all 
bees build alike with respect to the size of the cell and the 
angles at which its planes are inclined, so M. Reaumur 
found that all chickens chip the shell in the same direc* 
tion, from left to right; and that the circle in which 
they chip invariably cuts the e^g at right angles to its 
transverse axis, and not obliquely. The instrument which 



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NATURAL THEOLOGY. 3*73 

But admit the sparrow by some means to know 
that within that egg was concealed the principle 
'. of a future bird : from what chemist was she to 
lesmi that warmth was necessary to bring it to 
maturity, or that the degree of warmth imparted 
by the temperature of her own body was the de- 
gree required ? 

To suppose, therefore, that the female bird acts 
in this process from a sagacity and reason of her 
own, is to suppose her to arrive at conclusions 
which there are no premises to jvistify. If our 
sparrow, sitting upon her eggs, expect young 
sparrows to come out of them, she forms, I will 
venture to say, a vnld and extravagant expecta- 
tion, in opposition to present appearances and to 
probability; She must have penetrated into the 
order of nature farther than any faculties of ours 
will carry us ; and it hath been well observed, that 
this deep sagacity, if it be sagacity, subsists in 



the chicken employs is a small protuberauce on its upper 
mandible, called tbe hill-scale^ wbich bas no other use, 
and accordingly drops off soon after tbe bird is batcbed. 
If any one should consider tbis as a different operation in 
kind from tbose usually ascribed to instinct in animals 
tbat are formed, a little reflection will probably sbow 
him tbe impossibility of drawing any such line of dis- 
tinction. See tbe Dissertation on Instinct, Appendix. 



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374 NATURAL THEOLOGY. 

ooi^nctiiNi with great stupidity^ even iu relation 
to the same subject ''A chemical operation/' 
says Addison, '' could not be followed with greater 
art or diligence than is seen in hatching adiicken ; 
yet is the process carried on without the least 
glimmering of thought or common sense. The 
hen will mistake a piece of chalk for an egg — ^is 
insensible of the increase or diminution of their 
nnmber^-does not distinguish between her own 
and those of another species — is frightened when 
her stipposititious breed of ducklings take ihe 
water." 

But it will be said, that what reason could not 
do £nr the bird, observation, or instruction, or tra- 
dition might. Now if it be true that a couple of 
sparrows, brought up from the first in a state of 
separation from all other birds^ would build their 
nest, and brood upon their eggs, then there is an 
end of this solution. What can be the traditionary 
knowledge of a chicken hatched in an oven ? 

Of young birds taken in their nests, a few spe- 
cies breed when kept in cages ; and they which do 
so build their nests nearly in the same manner as 
in the wild state, and sit upon their eggs. This 
is sufficient to prove an instinct without having 
recourse to experiments upon birds hatched by 
artificial heat, and deprived from their birth of all 
communication with their species; for we can 



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NAT0JKAL THDOCOOr. 375 

hardly bring ourselves to believe tliat the parent 
bird informed her unfledged pupil of the history 
4>f her gestation^ her timely preparation of a nest, 
her exclusion of the eggs, her long incubation, and 
of the joyful aruption at last of her expected oflp- 
spring : all which the bird in the cage must have 
learnt in her infancy if we resolve her conduct into 
institution. 

Unless we will rather suppose that she remem- 
bers her own escape from the egg — had attentively 
observed ihe c&aSormaAion of the nest in whidi 
she was nurtured — and had treasured up her re- 
marks for future imitation; which is not only 
extremely improbable (ibr who that sees a brood 
of callow birds in their nest can helieve that they 
are taking a plan of their hiabitation ?) but leaves 
unaccounted for one principal part of the diffi- 
<^ulty, " the preparation of the nest before the 
laying of the egg." This she could not gain from 
observation in her infancy. 

It is remarkable also, that the hen sits upon 
eggs which she has laid without any communica- 
tion with the male, and which are therefore ne- 
cessarily unfruitful. That secret she is not let 
into. Yet if incubation had been a subject of 
instruction or of tradition, it should seem that 
this distinction would have formed part of the les- 
son : whereas the instinct of nature is calculated 



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376 NATURAL THKC«X)GY. 

for a stale of nature — the exception here alluded 
to taking place chiefly, if not solely, amongst do- 
mesticated fowls, in which nature is forced out of 
her course. 

There is another case of oviparous economy, 
which is still less hkely.to be the efiect of educa- 
tion than it is even in birds, namely, that of moths 
wid butterflies, which deposit their eggs in the 
precise substance — that of a cabbage, for example 
— from which, not the butterfly herself, but the 
caterpillar which is to issue from her egg, draws 
its appropriate food. The butterfly cannot -taste 
the cabbage ; cabbage is no food for her ; yet in 
the cabbage, not by chance, but studiously and 
electively, she lays her eggs. There are, amongst 
many other kinds, the willow-caterpillar and the 
cabbage-caterpillar; but we never find upon a 
willow the caterpillar which eats the cabbage, nor 
the converse. This choice, as appears to me, 
cannot in the butterfly proceed from instruction. 
She had no teacher in her cateiTpillar state. She 
never knew her pai*ent. I do not see, therefore, 
how knowledge acquired by experience, if it ever 
were such, could be transmitted from one genera- 
tion to another. There is no opportunity either for 
instruction or imitation. The parent race is gone 
before the new brood is hatched. And if it be 
original reasoning in the butterfly, it is profound 



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NATURAL THEOLOGY. 377 

reasoning indeed. She must remember her cater- 
pillar state^ its tastes and habits^ of which memory 
she shows no signs whatever. She must conclude 
from analogy (for here her recollection cannot 
serve her), that the little round body which drops 
from her abdomen will at a future period produce 
a living creature, not like herself, but Uke the 
caterpillar which she remembers herself once to 
have been. Under the influence of these reflec- 
tions^ she goes about to make provision for an 
order of things wliich she concludes will some 
time or other take place. And it is to be ob- 
served, that not a few out of many, but that all 
butterflies argue thus ; all draw this conclusion ; 
all act upon it. 

But suppose the address, and the selection, and 
the plan, which we perceive in the preparations 
i^hich many irrational animals make for their 
young, to be traced to some probable origin, still 
there is left to be accounted for that which is the 
jsource and foundation of these phenomena, that 
which sets the whole at work, the (jro^'/iy the pa- 
rental affection, which I contend to be inexpli- 
cable tipon any other hypothesis than that of 
instinct. 

For we shall hardly, I imagine, in brutes, refer 
their conduct towards their off'spring to a sense of 
duty or of decency, a care of reputation, a com- 



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378 NATURAL TttEOLOar. 

pliance with public manners, with public laws, at 
with rules of life built upon a long experience of 
their utility. And all attempts to account for the 
parental affection from association, I think, fail 
With what is it associated ? Most immediately 
with the thro€» of parturition, that is, with pain, 
and terror, and disease. The more remote, but 
not less strong association, that which depends 
upon analogy, is all against it. Everything else 
which proceeds from the body is cast away and 
rejected. In birds is it the egg which the heA 
loves ? or is it the expectation which she cherishes 
of a future progeny that keeps her upon her nestf 
What cause has she to expect delight firom her 
progeny ? Can any rational answer be given td 
the question, why, prior to experience, the brood- 
ing hen should look for pleasure from her chickens f 
It does not, I think, appear that the cuckoo ev^ 
knows her young ; yet, in her way, she is as carc- 
iiil in making provision for them as any othet 
bird. She does not leave her egg in every hote 
The salmon suffers no surmountable obstacle 
to oppose her progress up the stream of fresh 
rivers. And what does she do there ? She sheds 
a spawn, which she immediately quits in order to 
return to the sea; and this issue of her body she 
never afterwards recognizes in any shape what- 
ever. Where shall we find a motive for her eflfortb 



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J 



NATURAL TH£OL00Y. 379 

ftnd her perseveraace ? Shall we «eek it in argu- 
mentation or in instinct? The violet crab of 
Jamaica performs a fatiguing maroh of some 
months' continuance from the mountains to the 
sea-side. When she reaches the coast, she casts 
her spawn into the open sea, and sets out upon 
her return home. 

Moths and butterflies, as hatik already been 
observed, seek out for their eggs those precise 
situations and substances in which the offering 
caterpillar will find its appropriate food. That 
dear caterpillar the parent butterfly must never 
see. There are no experiments to prove that she 
would retain any knowledge of it if she did. How 
shall we account for her conduct ? I do not mean 
for her art and judgment in selecting and securing 
a maintenance £br her young, but fiDr the impulse 
upon which she acts. What shoidd induce her 
to exert any art, or judgment, or choice, about 
the matter ? The undisclosed grub, the animal 
which she is destined not to know, can hardly be 
the object of a particular affection, if we deny the 
influence of instinct. There is nothing therefore 
left to her, but that of which her nature seems 
incapable, an abstract anxiety for the general 
preservation of the species — a kind of patriotism 
— a solicitude lest the butterfly race should cease 
from the creation. 



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380 NATURAL THBOLOOV. 

Lastly, the principle of association will not ex- 
plain the discontinuance of the affection when the 
young animal is grown up. Association operating 
in its usual way would rather produce a contrary 
effect. The object would become more necessary 
by habits of society ; whereas birds and beasts^, after 
a certain time, banish their offspring, disown their 
acquaintance, seem to have even no knowledge of 
the objects which so lately engrossed the attention 
of their minds and occupied the industry and 
labour of their bodies. This change, in different 
animals, takes place at different distances of time 
from the birth ; but the time always corresponds 
Avith the ability of the young animal to maintain 
itself, never anticipates it. In the sparrow tribe, 
when it is perceived that the young brood can fly 
and shift for themselves, then the parents forsake 
them for ever ; and, though they continue to live 
together, pay them no more attention than they 
do to other birds in the same flock*. I believe 
the same thing is true of all gregarious qua- 
drupeds ". 

* GtoUsmith'g Natural Histor}', vol. iv. p. 244. 

'* In the natural and instinctive feelings of man, as 
contradistinguished from those which have been modified 
by reason, something of the same kind may be observed. 
The mutual relation of protection and dependence, pro- 



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NATURAL THEOLOGY. 381 

In this part of the case the variety of resources, 
expedients, and materials which animals of the 
same species are said to have recourse to under 
different circumstances, and when diflferently sup- 
plied, makes nothing against the doctrine of in- 
stincts. The thing which we want to account for 
is the propensity. The propensity being there, it 
is probable enough that it may put the animal 
upon diflferent actions according to different exi- 
gencies. And this adaptation of resources may 
look like the eflfect of art and consideration rather 
than of instinct; but still the propensity is in- 
stinctive. For instance, suppose what is related 
of the woodpecker to be true, that in Europe she 
deposits her eggs in cavities which she scoops out 
in the trunks of soft or decayed trees, and in 
which cavities the eggs lie concealed from the eye, 
and in some sort safe from the hand of man, but 
that, in the forests of Guinea and the Brazils, 
which man seldom frequents, the same bird hangs 

duced by power and weakness, is of this description. 
A helpless infant excites much stronger sympathy in the 
mother than the child that can shift for itself; and 
hence the partiality, accompanied by blindness to defects, 
which most parents entertain towards children whose 
natural deficiency, whether bodily or mental, throws 
them on their care long after the season of infancy. 



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382 NATURAL THEOLOGY. 

her nest on the twigs of tall trees, thereby placiAg 
them out of the reach of monkeys and snakes — i. e., 
that in each situation she prepares against the 
danger which she has most occasion to apprehend. 
Suppose, I say, this to be true, and to be alleged, 
on the part of the bird that builds these nests, as 
evidence of a reasoning and distinguishing pre- 
caution: still the question returns, whence the 
propensity to biiild at all ? 

Nor does parental affection accompany genera- 
tion by any universal law of animal organization, 
if such a thing were intelligible. Some animals 
cherish their progeny^ with the most ardent fond- 
ness, and the most assiduous attention; others 
entirely neglect them ; and this distinction always 
meets the constitution of the young animal with 
respect to its wants and capacities. In many, the 
parental care extendis to the young animal; in 
others, as in all oviparous iish^ it is confined to 
the egg, and even as to that, to the disposal of it 
in its proper element. Also, as there is genera- 
tion without parental affection, so is there parental 
instinct, or what exactly resembles it, without 
generation. In the bee tribe, the grub is nur- 
tured neither by the father nor the mother, but 
by the neutral bee. Probably the case is the 
same with ants. 

I am not ignorant of the theory which resolves 



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NATURAL THEOLOGY. 383 

instinct into sensation^ which asserts that what 
appears to have a view and relation to the future, 
is the result only of the present disposition of the 
animal's body, and of pleasure or pain experienced 
€tt the time. Thus the incubation of eggs is ac- 
counted for by the pleasure which the bird is sup- 
posed to receive from the pressure of the smooth 
convex surface of the shells against the abdomen, 
or by the reUef which the mild temperature of the 
egg may afford to the heat of the lower part of 
the body, which is observed at this time to be in- 
creased beyond its usual state. This present 
gratification is the only motive with the hen for 
sitting upon her nest; the hatching of the chickens 
is, with respect to her, an accidental consequence. 
The affection of viviparous animals for their young 
is in like manner solved by the relief, and perhaps 
the pleasure, which they perceive from giving 
suck. The young animal's seeking, in so many 
instances, the teat of its dam, is explained firom its 
sense of smell, which is attracted by the odour 
of milk. The salmon's urging its way up the 
stream of fresh- water rivers is attributed to some 
gratification or refreshment which, in this particu- 
lar state of the fish's body, she receives from the 
change of element. Now of this theory it may 
be said, — 

First, that of the cases which require solution. 



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384 NATURAL THEOLOGY. 

there are few to which it can be applied with 
tolerable probability ; that there are none to which 
it can be applied without strong objections, fiir- 
nished by the circumstances of the case. The 
attention of the cow to its calf, and of the ewe to 
its lamb, appear to be prior to their sucking. The 
attraction of the calf or lamb to the teat of the 
dam, is not explained by simply referring it to 
the sense of smell. What made the scent of milk 
so agreeable to the lamb that it should follow it 
up with its nose, or seek with its mouth the place 
from which it proceeded? No observation, no 
experience, no argument could teach the new- 
dropped animal that the substance from which 
the scent issued was the material of its food. It 
had never tasted milk before its birth. None 
of the animals which are not designed for that 
nourishment ever oflTer to suck, or to seek out 
any such food. What is the conclusion, but 
that the sugescent parts of animals are fitted 
for their use, and the knowledge of that use put 
into them ? 

We assert, secondly, that, even as to the cases 
in which the hypothesis has the fairest claim to 
consideration, it does not at all lessen the force 
of the argument for intention and design. The 
doctrine of instinct is that of appetencies, super- 
added to the constitution of an animal, for the 



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NATURAL THEOLOGY. 385 

effectuating of a purpose beneficial to the species. 
The above-stated solution would derive these 
appetencies from organization; but then this 
organization is not less specifically, not less 
precisely, and, therefore, not less evidently 
adapted to the same ends, than the appetencies 
themselves wovild be upon the old hypothesis. 
In this way of considering the subject, sensation 
supplies the place of foresight : but this is the 
effect of contrivance on the part of the Creator. 
Let it be allowed, for example, that the hen is 
induced to brood upon her eggs by the enjoy- 
ment or relief which, in the heated state of her 
abdomen, she experiences from the pressure of 
round smooth surfaces, or from the application 
of a temperate warmth. How comes this extra- 
ordinary heat or itching, or call it what you will, 
which you suppose to be the cause of the bird's 
inclination, to be felt just at the time when the 
inclination itself is wanted: when it tallies so 
exactly with the internal constitution of the egg, 
and with the help which that constitution re- 
quires in order to bring it to maturity ? In my 
opinion, this solution, if it be accepted as to the 
fact, ought to increase, rather than otherwise, our 
admiration of the contrivance '^•. A gardener light- 

^ Whether we regard the argument of existence, or 

s 



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366 NATURAL THBOLOOT. 

ing up his stores, just when he wants to force his 
fruit, and when his trees require the heat, gives 

of attributes, the truth here glanced at is of extreme im- 
portance, and it pervades the whole of Natural Theology. 
It will be more fully illustrated in the Appendix, and in 
the notes to the subsequent chapters. When sceptics 
think they have destroyed one reason for believing in 
the skill or in the goodness of the Deity, by an ex- 
planation of the means used for producing some given 
efibct, they only remove our admiration and our gratitude 
fifom one point to another, and often augment both the 
one and the other. Suppose it were discovered, contrary 
to all probability, that the bee makes the angles of 
109® 28' and 10° 32^ by means of some bodily con- 
finrmation which secures this result, — some form of its 
own parts answering to those angles, if such a thing 
can be conceived; the wonder is only removed from the 
working of the insect without a tool to its uung a tool 
provided for it by the intelligence which had solved the 
problem of maxima and minima, whence this conforma- 
tion is a corollary. Again, — ^the loss of one sense, as the 
sightit quickens our perceptions through the organs of 
those senses which remain, — as touch and hearing. It 
is most probable that this effect is produced by the in- 
fluence of habit, and has no direct connexion with the 
loss sustained. But habit might have had no such effect, 
and it might have blunted instead of sharpening; its 
effect tends to lessen the evil of the loss sustained ; and 
i^ pioduees this advantage just as much as if the c(»n- 



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NATURAL THEOLOGY. ^7 

act a more certain evidence of design. So again ; 
when a male and female sparrow come together, 
they do not meet to confer upon the expediency 
of perpetuating their species. As an abstract 
proposition, they care not the value of a barley- 
corn whether the species be perpetuated, or not : 
ihey follow their sensations, and all those conse- 
quences ensue, which the wisest counsels could 
have dictated, which the most sohcitous care of 
futurity, which the most anxious concern for the 

pensation had been the direct and immediate consequence 
of that loss. We are not here arguing the question of 
evil : that will be treated of hereafter, and it is common 
to both suppositions ; both to the case of immediate and 
of mediate compensation. Again, — suppose, in genera- 
lizing, we could resolve all intellectual phenomena into- 
some one principle, as association, — all moral into some 
other, as habit, — all physical into some third, as gravi- 
tation ; — nay, suppose the doctrines of some materiaUsts 
to prevail, and that all mental and all physical pheno- 
mena were resolvable into the operations of some subtile 
fluid, — this would surely not weaken the arguments for 
the unity of the Deity, if indeed it did not rather 
strengthen them; it would in no degree detract from 
otLr conviction of his skill, nor even of the variety of its 
operations ; and it would leave the argument as to good- 
nesft exactly where it stood before. — See Appendix, 
Dlisertation upon £vil. 

s2 



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3S8 NATURAL THEOLOGY. 

sparrow-world, could have produced. But how 
do these consequences ensue ? The sensations, 
and the constitution upon which they depend, are 
as manifestly directed to the purpose which we 
see fulfilled by them ; and the train of interme- 
diate effects as manifestly laid and planned with 
a view to that purpose : that is to say, design 
is as completely evinced by the phenomena, as it 
would be, even if we suppose the operations to 
begin or to be carried on, from what some will 
allow to be alone properly called instincts, that 
is, from desires directed to a future end, and hav- 
ing no accomplishment or gratification distinct 
from the attainment of that end. 

In a word: I should say to the patrons of 
this opinion. Be it so ; be it that those actions 
of animals which we refer to instinct are not gone 
about with any view to their consequences, but 
that they are attended in the animal with a pre- 
sent gratification, and are pursued for the sake 
of that gratification alone; what does all this 
prove, but that the prospection, which must be 
somewhere, is not in the animal, but in the Cre- 
ator? 

In treating of the parental aflFection in brutes, 
our business lies rather with the origin of the 
principle, than with the effects and expressions 
of it. Writers recount these with pleasure and 



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NATURAL THEOLOGY. 389 

admiration. The conduct of many kinds of 
animals towards their young has escaped no 
observer, no historian of nature " How will 
they caress them," says Derham, *^ with their 
affectionate notes; lull and quiet them with 
their tender parental voice ; put food into their 
mouths; cherish and keep them warm; teach 
them to pick, and eat, and gather food for them- 
selves ; and, in a word, perform the part of so 
many nurses, deputed by the Sovereign Lord and 
Preserver of the world to help such young and 
shiftless creatures !" Neither ought it, under 
this head, to be forgotten, how much the instinct 
costs the animal which feels it ; how much a bird, 
for example, gives up by sitting upon her nest ; 
how repugnant it is to her organization, her 
habits and her pleasures. An animal, formed 
for liberty, submits to confinement, in the very 
season when every thing invites her abroad; 
what is more, an animal delighting in motion, 
made for motion, all whose motions are so easy, 
and so free, hardly a moment, at other times, at 
rest, is, for many hours of many days together, 
fixed to her nest, as close as if her limbs were 
tied down by pins and wires. For my part, I 
never see a bird in that situation but I recog- 
nise an invisible hand, detaining the contented 
prisoner from her fields and groves, for the 



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390 NATURAL THEOLOGY. 

purpose, as the event proves^ the most wortii j 
of the sacrifice, the most important^ the most 
benefidaL 

But the loss of liberty is not the whole of what 
the procreant bird suffers. Harvey tells us that 
he has often found the female wasted to skin and 
bone by sitting upon her eggs. 

One observation more, and I will dismiss the 
subject. The pairing of birds, and the non-pair- 
ing of beasts, forms a distinction between the two 
classes, which shows that the conjugal instinct is 
modified with a reference to utility founded on 
the condition of the offspring. In quadrupeds, 
the young animal draws its nutriment from the 
body of the dam. The male parent neither does, 
nor can contribute any part to its sustentation. 
In the winged race, the young bird is supplied 
l)y an importation of food, to procure and bring 
home which, in a sufficient quantity for the de- 
mand of a numerous brood, requires the industry 
of both parents. In this difference, we see a 
reason for the vagrant instinct of the quadru- 
ped, and for the faithfiil love of the feathered 
mate. 



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NATURAL THECttXXJY. 3M 



CHAPTER XIX. 

OF INSECTS. 

We are not writing a system of natural his- 
tory ; therefore we have not attended to the 
classes into which the subjects of that science 
are distributed. What we had to observe 
concerning different species of animals> fell 
easily, for the most part, within the divisipnft 
which the course of our argument led us to 
adopt. There remain, however, some remarks 
upon the insect tribe, which could not prop^y 
be introduced under any of these heads; and 
which therefore we have collected into a chapter 
by themselves. 

The structure, and the use of the parts, of 
insects, are less understood than that of quadru- 
peds and birds, not only by reason of their mi- 
nuteness, or the minuteness of their parts (for 
that minuteness we can, in some measure, follow 
with glasses), but also by reason of the remote- 
ness of their manners and modes of life from 
those of lai^er animals. For instance : Insect^ 
under all their varieties of form, are endowed with 



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392 NATURAL THEOLOGY. 

anfenme^^f which is the name given to those long 
feelers that rise from each side of the head ; but 
to what common use or want of the insect kind 
a provision so universal is subservient has not 
yet been ascertained; and it has not been ascer- 
tained^ because it admits not of a clear, or very 
probable^ comparison, with any organs which we 
possess ourselves, or with the organs of animals 
which resemble ourselves in their functions and 
faculties, or with which we are better acquainted 

^ The most scientific entomologists consider the an- 
tennae of insects to be organs of hearing; this is the 
opinion of those who have minutely examined their 
structure ; whereas very many entomologists contend 
that the antennae are oi^ans of feeling, observing that 
many insects are constantly touching surrounding ob- 
jects with them, such as the bee tribe, ichneumonidae, &c. 
The argument used against the latter opinion is, that 
although many insects do undoubtedly touch surround- 
ing objects with their antennae, yet many scrupulously 
avoid so doing, such as the butterfly and moth tribe, 
the Lamellicorn beetles, &c. When, however, we are 
asked the question, what is hearing as distinguished 
from feeling, we find it difiicult to draw any line. Are 
they not mere modifications of the same thing ? and as 
the antennae of insects are so exceedingly variable in 
form, may they not be used as organs of touch in some^ 
and of hearing in others ? 



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NATURAL THEOLOGY. 393 

than we are with insects. We want a ground of 
analogy. Tliis difficulty stands in our way as to 
some particulars in the insect constitution, wliich 
we might wish to be acquainted with. Never- 
theless, there are many contrivances in the bodies 
of insects, neither dubious in their use, nor ob- 
scure in their structure, and most properly me- 
chanical. These form parts of our argument. 

I. The elytra, or scaly wings of the genus of 
scarabseus or beetle, furnish an example of this 
kind. The true wing of the animal is a light, 
transparent membrane, finer than the finest gauze, 
and not unlike it. It is also, when expanded, 
in proportion to the size of the animal, very large. 
In order to protect this delicate structure, and, 
perhaps, also to preserve it in a due state of 
suppleness and humidity, a strong, hard case is 
given to it in the shape of the homy ^nng which 
we call the elytron. When the animal is at rest, 
the gauze wings lie folded up under this impene- 
trable shield. When the beetle prepares for fly- 
ing, he raises the integument, and spreads out his 
thin membrane to the air. And it cannot be ob- 
served without admiration, what a tissue of cord- 
age, i, e. of muscular tendons, must run in vari- 
ous and complicated, but determinate directions, 
along this fine surface, in order to enable the 
animal, either to gather it up into a certain pre- 

s5 



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994 NATURAL THSOLOOr. 

086 form, whenever it desires to place its wiqgp 
under the shelter which nature hath given to 
them; or to expand again their folds when 
wanted for action. 

In some insects the elytra cover the whole 
bbdy**; in others, half; in others only a smali 
part of it'* ; but in all**, they completely hide and 
cover the true wings. Also, 

Many or most of the beetle species lodge in 

*• From this circumBtance beetles (the tribe of insects 
to which the above description applies) have received 
the name of ColeopterOj from two Greek words signify- 
ing sheath and wing, 

^ A tribe of insects called the Brachelytra (or Sto- 
phylinus of Linnaeus) possess wing cases of this de- 
scription. 

•* These are exceptions. In the genera MolorchuSy 
Sitaris (and others might be enumerated among the 
beetle tribe), the wing cases are small and narrow, and 
leave the wings exposed. The species of the genus 
Molorchusy however, do not require such protection for 
their wings, since they live in flowers. The habits of 
the Sitaris are not so well known ; they are said to live 
in the nests of certain species of bees. 

In the earwig the elytra do not entirely cover the 
wings ; but the portion of the wing exposed is of a horn- 
like substance, like the elytra, whilst the remaining 
part of the wing is extremely delicate. 



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NATURAL THEOLOGY% 



39S 



holes in the earthy environed by hard^ rough subr 
stances, and have frequently to squeeze their way 
through narrow passages; in which situation^ 
wings so tender, and so large, could scarcely 
have escaped injury, without both a firm covering 
to defend them, and the capacity of collecting 
themselves up under its protection ®^ 

II. Another contrivance, equally mechanical, 
and equally clear, is the awl, or borer, fixed at 




the tails of various species of flies; and with 
which they pierce, in some cases, plants; in 

^^ A tribe of beetles, coming under the generic name 
of Histery forms a good illustration of this mode of ex- 
istence : in these insects the elytra are remarkably hardw 

The species of the genus Hisler possess remarkable 
analogical resemblances to tortoises, which have some* 
what similar habits: Uke them, they are exceedingly 
hard, of an oval shape, and have the power of retracting 
the head beneath a horny covering ; they are slothfiil. 



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A 



396 NATURAL THEOLOGY. 

others, wood; in others", the skin and flesh of 
animals; in others, the coat of the chrysalis of 

and very strong, and burrow in the ground by means of 
their fore legs. 

A great analogical resemblance also exists between an 
insect called the mole-cricket and the mole, their habits 
also being similar. 

■■ Almost every caterpillar (perhaps, without excep- 
tion) has its peculiar parasites among the ichneumo- 
nidse, a different tribe of insects : the same ichneumon 
almost invariably choosing the same caterpillar to de- 
posit its eggs upon or in ; and as the situations in which 
different caterpillars feed are very various, so is the 
structure of their parasites. The ichneumons which in- 
fest internal feeding caterpillars (i. e., such as feed in 
the trunk of a tree, or the stem of a plant) are fur- 
nished with long ovipositors to enable them to reach the 
caterpillar through some hole or chink where they 
themselves cannot get. 

Even the ichneumons are not free from parasites. 
There are instances where four or five different para- 
sitical insects have been found in the same chrysalis 
(as that of the Trichiosoma leucoruniy a saw-fly), each 
one feeding upon the other. Thus several larvae of an 
ichneumon may be found feeding upon the inside of a 
chrysalis; and when these larvae turn into pupae or 
chr}'salides, some of the chalcididae, a different tribe of 
flies, will feed upon them, and even some of the last 
may in their turn be eaten up. 



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NATURAL THEOLOGY. 397 

insects of a different species from their own ; and 
in others, even lime, mortar, and stone®". I need 
not add, that having pierced the substance, they 
deposit their eggs in the hole. The descriptions 
which naturalists give of this organ are such as 
the following : It is a sharp-pointed instilment, 
which, in its inactive state, lies concealed in the 
extremity of the abdomen, and which the animal 
draws out at pleasure, for the purpose of making 
a puncture in the leaves, stem, or bark, of the 
particular plant, which is suited to the nourish- 
ment of its young. In a sheath, which divides 
and opens whenever the organ is used, there is 
inclosed a compact, solid, dentated stem, along 
which runs a gutter or groove, by which groove, 
after the penetration is effected, the egg, assisted, 
in some cases by a peristaltic motion, passes to 
its destined lodgment. In the oestrum or gad- 
fly, the wimble®* draws out like the pieces of a spy- 
glass : the last piece is armed with three hooks, 

" There is not any accredited instance of any insects 
perforating so hard a substance as stone, with the ' awl 
or borer' fixed at the tail. This instrument, technically 
called ovipositor, is excessively variable in its structure, 
being scarcely alike in any two species : the description 
given will answer for that of the saw-fly iTenthredo), 

" Whimble, or ovipositor. 



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396 NATURAL Tusauxkj. 

and is able to bore through the hide of an ox. 
Can any thing mcNre be necessary to display the 
mechanism, than to relate the fiftct? 

III. The iHngs*^ of insects, though for a dif- 
ferent purpose^ are, in their structure, not unlike 
the piercer. The sharpness to which the point 
in all of them is wrought ; the temper and firrn^ 
ness of the substance of which it is composed ; 
the strength of the muscles by which it is darted 
out, compared wiUi the smallness and weakness 
of the insect, and wiUi the soft and friable tex- 
ture of the rest of the body, — are properties (rf 
the sting to be noticed, and not a little to be 
admired. The sting of a bee will pierce through 
a goat-skin glove. It penetrates the human flesh 
more readily than the finest point of a needle. 
The action of the sting affords an example of the 
union of chemistry and mechanism, such as, if it 
be not a proof of contrivance, nothing is. First, 
as to the chemistry: how highly concentrated 
must be the venom^ which, in so small a quantity, 
can produce such powerful effects ! And in the 
bee we may observe that this venom is made from 
honey, the only food of the insect, but the last 
material from which I should have expected that 
an exalted poison could, by any process or diges- 

^ The stings of insects are also used as ovipositors. 



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NATURAL THEOLOGY. 999 

tion whatsoever, have been prepared. In the 
next place, with respect to the mechanism, the 
sting is not a simple but a compound instrument. 
The visible sting, though drawn to a point ex- 
quisitely sharp, is in strictness only a sheath, 
for, near to the extremity, may be perceived by 
the microscope two minute orifices, from which 
orifices, in the act of stinging, and, as it should 
seem, after the point of the main sting has 
buried itself in the flesh, are launched out 
two subtile rays, which may be called the 
true or proper stings, as being those through 
which the poison is infused into the puncture 
already made by the exterior sting. I have said 
that chemistry and mechanism are here united : 
by which observation I meant, that all this ma- 
chinery would have been useless, telum imbelle, 
if a supply of poison, intense in quality, in pro- 
portion to the smallness of the drop, had not 
been furnished to it by the chemical elaboration 
which was carried on in the insect's body; and 
that, on the other hand, the poison, the result of 
this process, could not have attained its effect, or 
reached its enemy, if, when it was collected at 
the extremity of the abdomen, it had not found 
there a machinery fitted to conduct it to the 
external situations in which it was to operate, 
viz. an awl to bore a hole, and a syringe t/O 



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400 



NATURAL THBOLOOT. 



inject the fluid. Yet these attributes, though 
eombincd in their action, are independent in 
their origfin. The venom does not breed the 
sting ; nor does the sting concoct the venom. 

IV. The proboscut^, with which many insects 
are endowed, comes next in order to be con- 
Fig. 1. Fig. 2. 




sidered. It is a tube attached to the head of 
the animal; in the bee, it is composed of two 

•• The part caUcd proboscis in the bee consists of a 
central stalk, or tongue, a, (Fig. 1,) and four lateral 
pieces, or jaws, two of which spring from the base, and 
two have their origin near the middle. The apical half 
of the stalk is soft and flexible, rather flat, and covered 
with minute hairs : it is chiefly this part of the proboscis 
which is used in collecting honey. Honey is not sucked 
up as is generally supposed, hut licked up, and then 
conveyed to the oesophagus. The four lateral pieces 
when closed form a sheath to protect the tongue, and 



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NATURAL THEOLOGY. 401 

pieces, connected by a joint: for, if it were con- 
stantly extended, it would be too much exposed 
to accidental injuries; therefore, in its indolent 
state, it is doubled up by means of the joint, and 
in that position lies secure under a scaly pent- 
house?'. In many species of the butterfly, the 
proboscis, when not in use, is coiled up like a 
watch-spring. In the same bee, the proboscis 
serves the office of the mouth, the insect having 
no other '°; and how much better adapted it is, 
than a mouth would be, for the collecting of 
the proper nourishment of the animal is suf- 
ficiently evident. The food of the bee is the 
nectar of flowers; a drop of syrup, lodged 
deep in the bottom of the corollas, in the re- 
cesses of the petals, or down the neck of a mo- 
nopetalous glove. Into these cells the bee 

other parts of the central stalk. Fig. 2 represents the 
profile of a butterfly's head ; a is the compound eye, and 
h the proboscis partially unfolded ; c and d show por- 
tions of the tubes forming the proboscis highly magnified. 

^ There is an indentation in the under side of the 
head to receive the proboscis when folded up. 

*" A bee has the same number of parts to its mouth 
as any other insect ; the only difference between that of 
a bee and a beetle is, that some of the parts are more 
developed in the former : viz.y the labium, tongue, and 
maxillae. 



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402 NATUBAL THEOLOGY. 

thrusts its long narrow pump, through the 
cavity of which it sucks** up this predous fluid, 
inaccessible to every other approach. It is ob- 
servable also, that the plant is not the worse** 

** See Note 86. It might be more correct to say 
lick upt for there is no tube. 

** Bees are essential to the fmctification of many 
sorts of plants, for it is by them that the farina is car- 
ried from the male to the female flowers; and as some 
flowers yield a much greater quantity of honey than 
others, it might perhaps be imagined that those yielding 
little, and yet depending upon the bees for their fruc- 
tification, might often be barren. No such defects, how- 
ever, are to be found : the structure of the proboscis 
varies considerably in different species of bees, so that 
all bees cannot collect indiscriminately from any honey- 
yielding plant. One great tribe of bees (the apidai) 
collect their honey for the most part from bell-shaped 
flowers, such as the blind-nettle, &c ; their long pro- 
boscis enabling them to reach the bottom of the bells. 
Another tribe, having the proboscis short, are obliged 
to collect from flowers of a different shape. There is 
yet another circumstance which leads the diflferent sorts 
of bees to visit a variety of flowers : viz,, that they ds 
not feed their larvue on the same substance. If we 
examine the cells of some (the andr^smdcgy, we And 
that the food stored up for the young consists of a ball 
of farina, which has scarcely any admixture of honey : 
these bees would naturally seek those flowers which 



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NATURAL THEOLOGY. 4ff8 

for what the bee does to it. The harmless plun- 
derer rifles the sweets, but leaves the flower un- 
injured. The ringlets of which the probosds of 
the bee is composed, the muscles by which it is 
extended and contracted, form so many micro- 
scopical wonders. The agility also with which 
it is moved can hardly fail to excite admiration. 
But it is enough for our purpose to observe, in 
general, the suitableness of the structure to the 
use of the means to the end, and especially the 
wisdom by which nature has departed from its 
most general analogy, (for animals being fiir- 
nished with mouths are such,) when the purpose 
could be better answered by the deviation. 

In some insects the proboscis, or tongue, or 
trunk, is shut up in a sharp-pointed sheath, which 
sheath", being of a much firmer texture than the 

yield the most farina ; whereas in others (the apidai) 
honey with very little farina is stored up for the young. 
•* The mouth of the common flea {Putex irritans) 
it of this nature ; it is composed of seven pieces, a pair 
of mandibles, a pair of maxillae, two palpi or feelers, 
and a tongue. The uses of these pieces appear to be as 
follows : — ^the mandibles, which are short, strong, and 
sharp, are to cut through the outer skin ; the maxilltff^ 
which are long and shaped like lancets, are to pierce 
still deeper so as to cause bleeding : the tongue is then 
used to lick and convey the blood to the oesophagus ; 



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404 NATURAL THEOLOGY. 

proboscis itself, as well as sharpened at the point, 
pierces the substance which contains the food, and 
then opens within the wound, to allow the enclosed 
tube, through which the juice is extracted, to per- 
form its office. Can any mechanism be plainer 
than this is, or surpass this ? 

V. The metamorphosis of insects from grubs 
into moths and flics is an astonishing process. A 
hairy caterpillar is transformed into a butterfly. 
Observe the change. We have four beautiful wings 
where there were none before — a tubular pro- 
boscis in the place of a mouth with jaws and teeth***, 

and the palpi are to direct these operations, conveying 
information to the animal by feeling or touch. These 
same seven parts (forming the mouth, and technically 
called trophi) are to be found in almost all insects, but 
constructed in different ways to suit the various habits 
of the species. 

^ The mouth of the caterpillar, or larva state of in- 
sects, has, in the greater portion of the species, the same 
number of parts as that of the perfect insect. In the 
pupa state some of these parts become nearly or quite 
obliterated, whilst others are much more developed to 
suit the habits of the animal in its next or perfect state 
of existence ; and thus, of course, in some instances, 
where there is but little difference between the habits of 
the larva and those of the perfect insect, there is like- 
wise but little difference in the structure of the mouth. 



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NATURAL THEOLOGY. 



405 



six long legs instead of fourteen feet. In another 
case we see a white, smooth, soft worm turned 



as, for instance, in locusts, grasshoppers, and cock- 
roaches. 

In the butterfly tribe the maxillae or under-jaws of 
the caterpillar become in the perfect insect elongated 
into two tubes (see Cut), which may be joined toge- 
ther at the pleasure of the animal, by means of pro- 
jecting ridges (furnished with a sort of hook somewhat 
like the laminae of feathers), in such a way as to leave 



et, -^A 




HUMBLE BER. 

a, a, mandtb'.es ; 

b, b, maxiUse ; 



c, c, maxillary palpi ; e, e, labial palpi ; 
«/, d, labium ; /, tongue ; ff, neck. 



a third tube between the two. It is through the central 
tube that the nectar is pumped or sucked up ; the two 



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406 NATURAL TBBOLOOT. 

into a black, hard, cnutaceous beetle with guuze 
wings. These, as I said, are astonidiing pro- 
cesses, and must require, as it should seem, a pro- 
portionably artificial apparatus. The hypothesis 
which appears to me most probable is, that, in 
the grub, there exist at the same time three ani- 
mals, one within another, all nourished by the 
same digestion, and by a commimicating circula- 
tion, but in diflTerent stages of maturity**. The 

outer tubes Reaumur imagines are for the reception of 
air; if this be the case, it may possibly be that air 
which is discharged from the central tuhe to create the 
necessary vacuum. The mandibles, or upper jaws, and 
other parts conspicuous in the caterpillar, are to be 
found only in a rudimentary state in the butterfly, — ^yet 
they do exist. 

•• The following observations do not exactly support 
the opinion of Dr. Paley. It is more probable that the 
parts which are to appear in the perfect insect do not 
exist in the larv8P., where there is not much difierence 
between the larva and pupa exceptiug at the time just 
previous to its becoming a pupa, at which time the larva 
is motionless and torpid. The caterpillar of a moth, 
when about to turn into a pupa, provides for the pro- 
tection of the latter state, either by surrounding itself 
with a web, or by some other means. Soon after this is 
accomplished the caterpillar becomes motionless, or 
nearly so ; it can neither eat nor crawl. At this time, 



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NATURAL THEOLOGY. 407 

latest discoveries made by naturalists seem, to 
favour this supposition. The insect already 
equipped with wings, is descried under the mem- 
branes both of the worm and nymph. In some 
qpecies the proboscis, the antennae, the Umbs, and 
wings of the fly have been observed to be folded 
up within the body of the caterpillar, and with 

and not 6e/br&, the parts of the pupa are formiDg within 
the skin of the caterpillar, which may be easily seen by 
dissection. When the difference between the larva and 
the perfect insect is great this is always the case, and 
the pupa is passive ; but when the difference is not so 
considerable the case is diflferent. The larva of a grass- 
hopper scarcely differs from the perfect insect it is to 
become, except in wanting wings; the pupa differs 
only in having rudimentary instead of perfect wings ; 
it casts its skin ; it is then the perfect insect, excepting 
that the wings are crippled, and these very rapidly ex- 
pand. In this latter case it is seen that there is but 
little difference between the three stages, and the change 
from the caterpillar to the moth is very great, and takes 
place only during the torpid state of the former, which 
state is to allow of its taking place. In the case of the 
grasshopper, where the changes are but slight, we should 
imagine but Httle of this torpidity would be required ; 
and such appears to be the case, for the pupee of grass- 
hoppers, and alhed insects, are always as active as either 
the larva or perfect insect. 



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408 NATURAL THEOLOGY. 

such nicety as to occupy a small space only under 
the two first wings. This being so, the outermost 
animal which, besides its own proper character, 
serves as an integument to the other two, being the 
farthest advanced, dies, as we suppose, and drops 
off first. The second, the pupa or chrysalis, then 
offers itself to observation. This also, in its turn, 
dies ; its dead and brittle husk falls to pieces, and 
makes way for the appearance of the fly or moth. 
Now if this be the case, or indeed whatever expli- 
cation be adopted, we have a prospective contri- 
vance of the most curious kind ; we have organ- 
izations three deep, yet a vascular system which 
supplies nutrition, growth, and life to all of them 
together. 

VI. Almost all insects are oviparous. Natiu'e 
keeps her butterflies, moths, and caterpillars locked - 
up during the winter in their egg-state ; and we 
have to admire the various devic(?s to which, if we 
may so speak, the same nature hath resorted for 
the security of the egg. Many insects enclose 
their eggs in a silken web; others cover them 
with a coat of hair torn from their own bodies ; 
some glue them together; and others, like the 
moth of the sUk-worm, glue them to the leaves 
upon which they are deposited, that they may not 
be shaken off by the wind, or washed away by 
rain. Some, again, make incisions into leaves. 



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NATURAL THEOLOGT. 409 

and hide an egg in each incision; whilst some 
envelope their eggs with a soft substance which 
forms the first aliment of the young animal ; and 
some again make a hole in the earth, and, having 
stored it with a quantity of proper food, deposit 
their eggs in it. In all which we are to observe, 
that the expedient depends not so much upon the 
address of the animal, as upon the physical re- 
sources of his constitution. 

The art also with which the young insect is 
coiled up in the egg presents, where it can be 
examined, a subject of great cimosity. The 
insect, furnished with all the members which it 
ought to have, is rolled up into a form which 
seems to contract it into the least possible space ; 
by which contraction, notwithstanding the small- 
ness of the egg, it has room enough in its apart- 
ment^ and to spare. This folding of the limbs 
appears to me to indicate a special direction ; for 
if it were merely the effect of compression, the 
collocation of the parts would be more various 
than it is. In the same species, I believe, it is 
always the same. 

These observations belong to the whole insect 
tribe, or to a great part of them. Other observa- 
tions are limited to fewer species, but not, per- 
haps, less important or satisfactory. 

I. The organization in the abdomen of the silk- 



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410 NATUEAL TH£CaX>OY. 

worm or ^ider, whereby these insects form their 
ihread, is as incontestably mechanical as a wire- 
<draw^*s milL In the body of the silkworm arc 




two bi^, rraoaxkable for their form, position^ and 
4ise. They wkicl round the intestine; when drawn 
out they are ten inches in lengthy though the ani- 
mal itself be only two. Within these bags is col- 
lected a glue ; and« communicating witii the bags, 
are two paps or outlets, perforated like a grater 
by a number of small holes. The glue or gum, 
beiBg passed through t\kese minute apertures, 
fonns hairs of ^Jmost imperceptiUe fineness ; and 
these hairs, wh^i joined, compose the silk which 
wre wiad off frcwa the cone in whid^ the silkworm 
ttas wrapped itself up : in the spider, the wdb is 
Sormed from this tlnread. In both cases, the ex- 
tremity 4»f the thread, by means of its adhesire 
quality, is fin^ attached by the animal to some 
^extemal hold; ajad the end being now fastened 
to a point, the insect, by turning round its bodj^ 
or by reeedio^ from that point, draws out the 
thread through the holes above described, by an 
operation, an hath been observed^ exactly similar 
to the drawing of wire. The thread, like the wire, 
ii&xmedbytbohoLetfarmigh which it pasaes. In 



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NATURAL THBOLOGY. 411 

offie ra^pect there is a difference. The wire is the 
ttietal unalt^^ed, except in figure. In the animal 
process the nature of the substance is somewhat 
changed as well as the form; for, as it exists 
within the insect, it is a solft, clammy gum cir 
glue. The thread acqmres^ it is probable, ite 
firmness and tenacity from the action of the air 
npon its surface in the moment of exposure ; and 
a thread so fine is almost all surface. This pro- 
perty, however, of the paste is part o£ the con- 
trivance. 

The mechanism itself consists of the bags or 
reservoirs into which the glue is odlected, and 
of the external holes communicating with these 
bags ; and the action of the machine is seen in 
the fOTming of a thread, as wire is formed, by 
forcing the material already prepared through 
holes of proper dimensions. The secretion is an 
act too subtile for our dMJcemment, except as we 
perceive it by the produce. But one tiling mor 
sweru to another; the secretory gk,nds to the 
quality and consistence required in the secreted 
substance ; the bag to its rec^tion. The oiirtlets 
and orifices are constructed not merdy for reliet^ 
ing the reservoirs of their burden, but t&£ manu- 
facturing Hie contontiB into a form and textnte of 
great external nse, or ntther, indeed, of 6it«m Mh 
cemty, to tfae life md fioRtiNiM of the iiuteet 

t2 



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412 NATURAL THEOLOGY. 

II. Bkes, under one character or other^ have 
furnished every naturalist with a set of observa- 
tions. I shall, in this place, confine myself to 
one; and that is the relation which, obtains be- 
tween the wax and the honey. No person who 
has inspected a bee-hive can forbear remarking 
how commodiously the honey is bestowed in the 
comb, and, amongst other advantages, how effec- 
tually the fermentation of the honey is prevented 
by distributing it into small cells. The fact is, 
that when the honey is separated from the comb, 
and put into jars, it runs into fermentation with a 
much less degree of heat than what takes place in 
a hive. This may be reckoned a nicety ; but, in- 
dependently of any nicety in the matter, I would 
ask, what could the bee do with the honey if it 
had not the wax? how, at least, could it store 
it up for winter? The wax, therefore, answers 
a purpose with respect to the honey; and the 
honey constitutes that purpose with respect to 
the wax. This is the relation between them. 
But the two substances, though together of the 
greatest use, and without each other of little, come 
from a different origin. The bee finds the honey, 
but makes the wax. The honey is lodged in the 
nectaria of fliowers, and probably undergoes little 
alteration — ^is merely collected; whereas the wax 
is a ductile tenacious paste, made out of a dry 



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NATURAL THEOLOGT. 413 

powder •*, not simply by kneading it with a liquid, 
but by a digestive process in the body of the bee. 
What account can be rendered of facts so circum- 
stanced, but that the animal, being intended to 
feed upon honey, was, by a peculiar external con- 
figuration, enabled to procure it? That, more- 
over, wanting the honey when it could not be pro- 
cured at all, it was further endued with the no less 
necessary faculty of constructing repositories for 
its preservation?- Which faculty, it is evident, 
must depend primarily upon the capacity of pro- 
viding suitable materials. Two distinct functions 
go to make up the ability. First, the power in 
the bee, with respect to wax, of loading the farina 
of flowers upon its thighs. Microscopic observers 
speak of the spoon-shaped appendages with which 
the thighs of bees are beset for this very purpose ; 
but, inasmudi as the art and will of the bee may 
be supposed to be concerned in this operation, 
there is, secondly, that which doth not rest in art 
or will — a digestive faculty, which converts the 
loose powder into a stiff substance. This is a just 

•* The opinion of Huber, Hunter, and others, is, that 
wax is not made out of pollen^ but from honey. Huber 
kept some bees confined, and fed them with honey only, 
and wax was secreted as usual. It is most likely that 
lees never eat farina, and that it is collected from the 
larvae only. See article Bee, * Penny Cyclopaedia.* 



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414 NATURAL THXOLOOT. 

account of the honej md the honey^tomb ;. and 
this acoount, through eveiy part, carries a creativ9. 
iBtelligience along with it **. 

The niinff also of the bee has thk relation to 
the honey, that it is necessary for the protectioB* 
of a treasure which invites so many robbers. 

III. Our business is with mechanism. In tibe^ 
panorpa tribe of insects, there is a forceps in the 
tail of the m^e insect with which he catches and 
holds the female. Are a pair of pincers more me- 
chanical than this provision in its structure ? or 
is any structure more clear and certain in its 
design**? 



^ It has often been remarked, that Dr. Paley does 
not either in this chapter, or in that on instinct, state 
the most remarkable of all instincts, and of all the la« 
hours of insects, the formation of the cells by the bee, 
according to the strictest geometrical rules. The history 
of this discovery made (through Reaumur's suggestion) 
by Koenig's application of the fluxional calculus, and by 
its result being found to tally with Maraldi's measure- 
ment, will be given in the Appendix. Maclaurin solved 
the same problem afterwards by the help of plane geo- 
metry, with a truly felicitous skill. The angles actually 
made differ by about two minutes from those given by 
the calculus; but no one can doubt that subaaquent 
discovery, will explain this. 

** In die genus TricMus (a tribe of beedes oloiely. 



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NATTTRAI. THEOLOGY. 4lS 

W. St. Pierre teUs us* that in a ffy with stt 
feet (I db not rememBer iJia* he describesr the 
species), the pair next the head and the pair* next! 
the tail have brushes at their extremities, witfr 
which the fly dresses, as there may be occasion; 
the anterior or the posterior part of its body ; but 
that the middle pair have no such brushes, tho' 
situation of these legs not admitting of the brushesf, 
if they were there, being con verted'to the same use: 
This is a very exact mechanical distinction' •'^. 

V. If the reader, looking to bur distributions 
of science, wish to^ contemplate the chemistry as 
well as the mechanism of nature; the iriseijt cretf- * 
tion will afford him an example. I refer to the 
light in the tail of a glow-worm. Two points seem 
to be agreed upon by naturalists concerning it: 

allied to the rose beetle) the males have the tibifi& of the 
middle pair of legs curved for the same purpose. 

^ The stag-beetle (^Lucanus cervus) cleans its- an- 
tennae " by drawing them between the thigh of the fore- 
leg and the underside of the thorax, in both of whicH 
parts a velvet-like pAteh of hair i» to/bie obberveid^ whidi 
is weH 8di4)ted for such purpose.'^ See this, aud^ other 
peculiarities in ^ same insect, in the first Part of the 
Entkimologioal Society's Transacti^as^ in ' The Joiirut^. 
of Proceedings,' page^ 6^ 

*Voia.p.342. 



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416 NATURAL THBOLOGT. 

first, that it is phosphoric ; secondly, that its use 
is to attract the male insect. The only thing to 
be inquired after is the singularity, if any such 
there be, in the natural history of this animal, 
which should render a provision of this kind m6re 
necessary for it than for other insects. That sin- 
gularity seems to be the difference which subsists 
between the male and the female, which difference 
is greater than what we find in any other species 
of animal whatever. The glow-worm is a female 
caterpillar, the male of which is B,fly, lively, com- 
paratively small, dissimilar to the female in ap- 
pearance, probably also as distinguished from her 
in habits, pursuits, and manners, as he is unlike 
in form and external constitution. Here then is 
the adversity of the case. The caterpillar cannot 
meet her companion in the air. The winged rover 
disdains the ground. They might never there- 
fore be brought together did not this radiant 
torch direct the volatile mate to his sedentary 
female ••. 



•• The female glow-worm undergoes the same trans- 
formations as all other insects, and its perfect state 
differs considerably from its larva or caterpillar state, 
though in both stages it emits the phosphoric light. 
Besides the ordinary sexual distinctions, the female 
glow-worm differs from the male only in being apterous; 



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NATURAL THEOLOGY. 417 

In this example we also see the resources of art 
anticipated. One grand operation of chemistry 
is the making of phosphorus ; and it was thought 
an ingenious device to make phosphoric matches 
supply the place of lighted tapers. Now this very 
thing is done in the body of the glow-worm. The 
phosphorus is not only made> but kindled, and 
caused to emit a steady and genial beam, for the 
purpose which is here stated^ and which I believe 
to be the true one •*. 

VI. Nor is the last the only instance that en- 
tomology affords^ in which our discoveries, or 

but apterous female insects are not unfrequent; thus 
many species of moths have no wings. The two cir- 
cumstances of the sedentary habits of the female, and 
the males flying by night only, seems to show the use of 
the light. See the next note. 

^ There exists some controversy among naturalists as 
to the use of the glow-worm's light. The doubt has 
been chiefly raised by the observation that the insect is 
luminous, though in an imperfect degree, when in the 
state in which it cannot propagate, as mentioned in the 
last note ; and that other insects are attracted by light 
as well as the male glow-worm. The preponderance 
of the argument is decidedly in favour of the supposition 
adopted by our author, and which is also the commonly 
received opinion. The particulars of the discussion will 
be given in the Appendix. 

t5 



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418 NATnUMsTHBObOOT. 

rather owr proj^ciisi bm out. to W inutatkma of 
nulure. Some years ago> a.{>laii was sv^pgeatecl 
of produciog propulskm by redaction in thia wigr :. 
by the force of a &team-caigiiie> a stream of water* 
waa to be shot out of the stem of a boat».the im* 
pulse of whieh stream upon the water in the rivi^- 
was to push the boat itself fcnrward; it is in: truth 
the principle by which sky-rockets ascend in the- 
ain Of the use or practicability of the plan I; am. 
not speaking; nor is it my concern to praise its 
ingenuity ; but it is certainly a contrivanoe. Now^ 
if naturalists are to be beUeved, it is exaotly the . 
device-which. nature has. made use of for the mo- . 
tion of some species of aquatic insects. The larva 
of the dragmi-flif, according to Adams> swims by 
ejecting water from its. tail— is driven forward by 
the re-aetion of water in the pool upon the current 
issuing in a direction backward from its body. 

VII; Again : Europe has lately been surprised 
by the elevation of bodies in the air by means of a 
balloon. The discovery consisted in finding out 
a manageable substance, which was, bulk for bulk, 
lighter than air ; and the application of the dis- 
covery was to make a body composed of this sub- 
stance bear up, along with its own weight, some 
heavier body which was attached to it. This ex- 
pedient, so new to us> proves to be no other than . 
what the Author of nature has employed in the 



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gossamer spider. We frequently see this spider's 
tiiread floating in tiie air^ and extended^ from 
hedge to hedge aerossr a road or brook> of four or 
five yards width. The animaL whidi forms^ the- 
thread has no wings wherewith to fly fr(Mn< on&' 
extremity to the other of this line, nor muscleer to 
enable it to spring or dart to so great a distance : 
yet its Creator hatlulaid forit apath in the atmo- 
sphere; and after thiff^nHainer. Though the ani- 
mal itddf be header Uianain the thread which it 
spins from iti^bowi6l& is- specifically Ughter. This 
is iis^ baUoen. The spider^ left to itself would^'' 
dmp to the grcrand; bat bdingtted toits thready 
both are^supported. We hskve here avery pecu- 
liar provmon; and to a contemplative eye it is a 
gratifying spectacle to see this insect wafted on 
her thread, sustained by a levity not her own, and 
traversing regions which, if we examined* only the 
body of the animal, might seem to have been for- 
bidden to its nature ^®®. 

*~ It was at one time supposed that the spider coul4 
project its thread through the air at will in any direc- 
tion, and thus attaching it to diflerent bodies, move from 
one to the other. Ilie observations more accurately 
made of late years, show that this power is not pos- 
sessed by the animal, bHt that it requires the aid (^^a. 
current of air to direct the thread. This correcttoB,. 
however, of the former o]^ni6n, in no way weakens- the* 
foioe of the argunient in the text. 



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420 KA^URAL THEOLOGY. 

i ' 

I must now cfave the reader^s permission to 
introduce into t^. place, for want of a better, an 
^observationor two upon the tribe of animals, 
whether belonging to ''land or water, which are 
covered by «i^i&. • . 




Helix atperta of Muller,— ;Coinmon (garden snail ; but the cut re- 
presents what b called a left-handed shell, and a rarity. 

I. The shells of snails are a wonderful, a me- 
chanical, and, if one might so speak concerning 
the works of nature, an original contrivance. 
Other animals have their proper retreats, their 
hybemacula also, or winter-quarters, but the snail 
carries these about with him. He travels with 
his tent ; and this tent, though, as was necessary, 
both light and thin, is completely impervious 
either to moisture or air. The young snail comes 



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NATURAL THEOLOGY. 421 

out of its egg with the shell upon its back; and' 
the gradual enlargement -which.- the shell receives 
is derived from the^ slime e^^creted by the ani- 
maVs skin. Now the aptness of this excretion 
to the purpose, its property of hardening into a 
shell, and the action^ whatever it bej of. the ani- 
mal, whereby it avails itself of its gift> and of the 
constitution of its glands ^to say nothing of the 
work being commenced befote the a^nimal is bbrh), 
are things which can, with no probability, be 
, referred' to- any other cause' than to exprelss 
design ; and that not on the par,t of the animal - 
alone, in which design, though it might build the 
house, it could not have supplied the material. 
The will of the animal could not determine the 
quality of the excretion. Add to which, that the 
shell of the snail, with its pillar and convolution^ 
is a very artificial fabric; whilst a snail, as it 
should seem, is the most numb and unprovided 
of all artificers. In the midst of variety there is 
likewise a regularity which could hardly be ex- 
pected. In the same species of snail the number 
of turns is usually, if not always, the same. The 
sealing up of the mouth of the shell by the snail 
is also well calculated for its warmth and security ; 
but the cerate is not of the same substance with 
the shell. 

II. Much of what has been observed of snails 



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422 



NATURAL THECMiOeT. 



belongs to shell^fiMh and. their tkelUi particulaiiy 
to dioee of the univalve land ; with the additioH 




Sfomdyhu — prickly oyster. 

of two remarks— one of which is upon the great 
strength and hardness of most of these shells. I 
do not know whether, the weight being given, art 
can produce so strong a case as are some of these 
shells; which defensive strength- suits well with 




Ottrea crista galii, of Lamarck^ Mytiiut crittagalii of Linnaus— • 
tbe cock^-comb oysttr. 



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NAS^BAL TflBDL06Y« 4Z^. 

the life of an animal that haa- often to suirtain the^ 
danger&^of a stormy element and a rocky bottoin>. 
as well as the attacks of voracious fish. The 
other remark is upon, the property, in the animal 
excretion^ not only, of congealing, but of congeal- 
ing or, ai» a builder would call it, setting, in water, 
and into a cretaceous substance, firm and. hard, v 
This property is much more extraordinary, and, 
chemically speaking, more specific, than that of 
hardening in the air, which may be reckoned a 
kind of exsiccation, like the drying of clay into 
bricks. 

III. In the bivalve order of sheU-fish, cockles, 
mussels, oysters, &c., what contrivance can be so 
simple or so clear as the insertion, at the back, of 




Cardium cardma — Venus' heart ix)ckle. 

a. tough tendinous substance that becomes at once/ 
the ligament which binds the two shells tc^ether^. 
and the hinge upon which they open and shut ? 
ly. The shell of a lobster's tail, in its articular r 



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424 NATURAL THEOLOGY. 

tioDS and oTerlappings, represents the jointed part 
of a coat of mail ; or rather, which I believe to be 
the truth> a coat of mail is an imitation of a lob- 
sterns shell. The same end is to be answered by 
both ; the same properties, therefore, are required 
in both, namely, hardness and flexibility — a co- 
vering which may g^ard the part without obstruct- 
ing its motion. For this double purpose the art 
of man, expressly exercised upon the subject, has 
not been able to devise anything better than what 
nature presents to his observation. Is not this 
therefore mechanism, which the mechanic, having 
a similar purpose in view, adopts ? Is the struc- 
ture of a coat of mail to be referred to art ? Is 
the same structure of the lobster, conducing to 
the same use, to be referred to anything less than 
art? 

Some who may acknowledge the imitation, and 
assent to the inference which we draw from it in 
the instance before us, may be disposed, possibly, 
to ask, why such imitations are not more frequent 
than they are, if it be true, as we allege, that the 
same principle of intelligence, design, and mecha- 
nical contrivance was exerted in the formation of 
natural bodies as we employ in the makihg of 
the various instruments by which our purposes are 
served ? The answers to this question are, first, 
that it seldom happens that precisely the same 



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NATURAL THEOLOGY. 425 

purpose, and no other, is pursued in any work 
which we compare of nature and of art ; secondly, 
that it still more seldom happens that we can imi- 
tate nature if we would. Our materials and our 
workmanship are' equally deficient. Springs and 
wires, and cork and leather, produce a poor sub- 
stitute for an arm or a hand. In the example 
which we have selected, I mean a lobster's shell 
compared with a coat of mail, these difficulties 
stand less in the way than in almost any other 
that can be assigned ; and the consequence is, as 
we have seen, that art gladly borrows from nature 
her contrivance, and imitates it closely. 



But to return to insects. I think it is in this 
cla«s of animals above all others, especially when 
we take in the multitude of species which the 
microscope discovers, that we are struck with what 
Cicero has called " the insatiable variety of nature." 
There are said to be six thousand species of flies ; 
seven hundred and sixty butterflies ; each different 
from all the rest (St. Pierre) "^ The same writer 

*•' There are collections of insects in this country 
which, in all probability, contain forty thousand species. 
The number of species in existence may fairly be 
reckoned at sixty or eighty thousand. Mr. Stephens, in 
his catalogue of British insects, enumerates ten thou- 



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42& NATITRAL THEOI.OS7. 

teHs US, from his own obsenraiioii, that iJihdy- 
seven species of wmged insects, with distinctionB 
well expressed, visited a single s t r awber r y- plant 
in the conTse of three weeks*. Ray observed, 
within the compass of a mile or two of his owtt 
house, two hundred kinds of butterffies *•*, noc^ 
tumal and diurnal. He likewise asserts, but, I 
think, without any grounds of exact computation, 
that the number of species of insects, reckoning idl 
sorts of them, may not be short of ten thousandf. 
And in this vast variety of animal forms (for the 
observation is not confined to insects, though 
more applicable perhaps to them than to any- 
other class), we are sometimes led to take notice of 
the different methods, or rather of the studioiudy 
diver»fied methods, by which one and the same 
purpose is attained. In the article of breathings 
for example, which was to be provided for in. some 

sand, since the publication of which many new species 
have been disoovered* We are now e|>ealQng of tme 
iiiseets, — animals having six legs, Ac., — and not inclnd*- 
ing crabs, spiders, scorpions, and others, which have 
been classed with insects. 

*" Eay must mean butterflies and moths^ — we have 
not one hundred species of butterflies in this country f 
and besides, no butterflies are ** nocturnal." 

* VoLLp.3, t Wild. «f God, .p. 28. 



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NATURAL THBOLOOT. 427' 

way or other, besides the ordinary Tavieties of 
lungjs^ gillB> and breathing^holes (for insects in, 
general respice> not by the mouth, but throu^ 
holes in the sides), tl^ nymphse of gnats have an 
apparatus to raise their backs to the top of the 
water, and so talie breath. The hydroeanthari 
do the like by ilirusting their tails out of the 
water."*" The maggot of the eruca. labra has a 
long tail, one part sheathed within another (but 
which it can draw out at pleasure), with a starry": 
tuft at the end, by which tuft, when expanded 
upon the surface, tUe insect both supports itself 
in the water, and draws in the air which is neces** 
sary. In the article of natural clothing, we haire 
the skins of animals inyested with scales, hair; 
feathers, mucus, froth, or itself turned into a i^eE- 
or crust. In the no less necessary article of 
offsnce and defence, we have teeth, talons, beaks, 
horns, stings, prickles, with (the most singular 
expedient for the same purpose) the power of 
giving the electric shock, and, as is credibly re- 
lated of some animals, of driving away their pur- 
suers by an intolerable foe tor, or of blackening 
the water through which they are pursued. The 
consideration of these appearances might induce 
us to believe that variety itself, distinct irom 
every other reason, was a motive in the mind of 
the Creator;, or with the agents of his will.. 
* DochaiB, p. 7. 



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428 NATURAL THBOLOGT. 

To thk g^reat rariety in organised life the Deity 
has given, or perhaps there arises out of it, a cor- 
responding variety of animal appetUe$. For the 
final cause of this we have not far to seek. Did 
all animals covet the same element, retreat, or 
food, it is evident how much fewer could be sup- 
plied and accommodated than what at present 
live conveniently together, and find a plentiful 
subsistence. What one nature rejects another 
delights in. Food which is nauseous to one tribe 
of animals becomes, by that very property which 
makes it nauseous, an alluring dainty to another 
tribe. Carrion is a treat to dogs, ravens, vultures, 
fish ^^. The exhalations of corrupted substances 
attract flies by crowds. Maggots revel in putre- 
faction "*. 

*• Very many insects subsist entirely upon carrion, 
both in the larva and imago state, and in hot weather 
must be highly serviceable in removing such noxious 
substances. In this point of view the mi^gots of flies 
are exceedingly useful; a carcase becoming speedily 
threaded in every direction by them, is soon either de- 
voured or wasted. 

*•* The most remarkable circumstance relative to in- 
stinct, as well as to the habits of insects, the architec- 
ture of the bee, has been observed upon in a former 
note. The manufacture of the wasp perhaps comes 
next, and is to the chemistry what the former is to the 
mathematics of instinct. It furnishes, too, one of the 



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NATURAL THEOLOGY. 429 

most striking instances of the discoveries of man having 
been anticipated by the lower animals; and is another 
remarkable proof how many more might have beep 
made by closely attending to their habits,— -perhaps a 
more remarkable proof than those referred to in the text 
of this chapter, and hinted at in chapter viii., where the 
author is treating of the vertebrae and ribs. It is cer- 
tain that some of the most material improvements in 
paper-making recently introduced, as the use of other 
substances besides rags, and the obtaining toughness 
by means of long fibres, had been known to the wasp 
from its first creation. Its whole process in making 
what is called wasp-paper is precisely that of the best 
paper-makers. This will be illustrated in the Ap* 
pendix. It is only mentioned here as another among 
the striking instances of the Divine agency through the 
operations of unreasoning animals — instances which fill 
the contemplative mind with the most profound and 
pleasing admiration, and dispose it to the enjoyment and 
the duty of heartfelt devotion. 

The migration of birds is another subject full of in- 
struction regarding the great questions connected with 
instinct, and is reserved for the Appendix. Observation 
seems at variance with the notion of the older birds 
teaching the yearlings; indeed, the two classes have 
been found not to travel together. But the agitation 
imiversally observed in birds of passage kept in cages, 
at the season of migration, proves clearly that no ex- 
perience nor instruction will account for the change of 
place. See Mr. W. Herbert's excellent remarks on this 



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490 KATORAL THBOLOGT. 

iMtiiict, «Bd on the similar instmotn inspecting choioe 
of food, which nwket bifds bred in a cage at once select 
their appomted food when thowa them Ur tJ» firat 
time. White** Selbovme, edit. 1833, p. 41, et teq. 
The facts respectiBg carrier-pigeoBs and odier sonmals 
finding their way thnnigh oountries in the lniowle<%e 
of which &ey never could hare been trained, belong 
to the same clasB, and will be particularly disscussed 
in the Appendix — Dissertation upon Instinct. 

Hie doctrine of conflicting instincts will be considered 
under the head of conflicting contrivances in the Dis- 
sertations upon Evil, and adverted to in the Notes on 
the last Chapter. Such apparent conflicts afford no 
ground whatever for the sceptical argument as to de- 
sign; and they in no way strengthen the sceptical 
argument drawn, and inaccurately drawn, from other 
sources, respecting benevolence. 



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NATURAL TUBOLOGT. 431 



CHAPTER XX. 

OF PLANTS. 

I THINK a designed and studied mecla^anism to be 
in general more evident in animals than in plants ; 
and it is unnecessary to. dwell upon a weaker ar- 
gument where a stronger is at hand. There are^ 
however^ a few observations upon the vegetable 
Idngdom which lie so directly in oiu: way^ that it 
would be improper to pass by them without notice. 
The one great intention of nature in the struc- 
ture of plants seems to be the perfecting of the 
^eed^ and^ what is part of ihe same intention^ the 
{^reserving of it until it be perfected. This inten- 
tion shows itself, in the first place, by the cace 
which a{^pears to be taken to piH>tect and ripen, 
by every advantage which can be given to them 
q£ situation in the plant, those parts which most 
immediately contribute to fructification, vis*, the 
anthane;, the stamina, and the stigmata. These 
parts are usuidly lodged in the centre, the recesses, 
or the labyrinths of the flower — during their ten- 
der and immature state are shut up in the stalk, 
or sheltered in the bud — as soon as they have 



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432 NATURAL THEOLOGY. 

acquired finnness of texture sufficient to bear ex- 
posure, and are ready to perform the important 
office which is assigned to them, they are disclosed 
to the light and air by the bursting of the stem 
or the expansion of the petals ; after which they 
have, in many cases, by the very form of the 
flower during its blow, the light and warmth re- 
flected upon them firom the concave side of the 
cup. What is called also the sleep of plants is 
the leaves or petals disposing themselves in such 
a manner as to shelter the young stems, buds, or 
fruit. They turn up, or they fall down, according 
as this purpose renders either change of position 
requisite. In the growth of corn, whenever the 
plant begins to shoot, the two upper leaves of the 
stalk join together, embrace the ear, and protect 
it till the pulp has acquired a certain degree of 
consistency. In some water-plants the flowering 
and fecundation are carried on within the stem, 
which afterwards opens to let loose the impreg- 
nated seed*. The pea, or papilionaceous, tribe 
enclose the parts of fructification within a beauti- 
fid folding of the internal blossom, sometimes 
called, from its shape, the boat or keel — ^itself also 
protected under a penthouse formed by the exter- 
nal petals. This structure is very artificial; and 

* Philot. Trmniact. ptrt ii. 1796, p. 502. 



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NATURAL THEOLOGY. 433 

what adds to the value of it^, though it may dimi- 
nish the curiosity, very general. It has also this 
further advantage (and it is an advantage strictly 
mechanical), that all the blossoms turn their backs 
to the wind whenever the gale blows strong enough 
to endanger the delicate parts upon which the 
seed depends. I have observed this a hundred 
times in a field of peas in blossom. It is an apti- 
tude which results from the figure of the flower, 
and, as we have said, is strictly mechanical, as 
much so as the turning of a weather-board or tin 
cap upon the top of a chimney. Of the poppy, 
and of many similar species of flowers, the head 
while it is growing hangs down, a rigid curvature 
in the upper part of the stem giving to it that 




Papaver rheeai — ^Poppy. 

U 



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434 NATURAL THEOLOGY. 

potitiott; and in that positioii it is impeiietraUb 
by rain or moisture. When die head has acqnked 
its size and is ready to open, the stalk erects itsdf 
iat the purpose, as it shouhi seem, of presenting 
the flower, and with the flower the instruments of 
fiructification, to the genial influence of the 8un!s 
rays. This always struck me as a curious ]»i- 
perty, and specifically as wdl as originaliy pro- 
vided for in the constitution of the plant ; for if 
the stem be only bent by the we^ht of the head* 
how comes it to straighten itself when the head is 
the heaviest 7 These instances show the attention 
<rf nature to this principd. object, the safely and 
maturation of the parts iqpon whieh &e seed 
depends. 

In trees, especially in those which axe natives 
of colder climates, this point is taken up earlier. 
Many of these trees (observe in particular the 
ash and the horte-chesfyiut) produce the embryos 
of the leaves and flowers in one year, and bring 
them to perfection the following. There is a 
winter therefore to be gotten over. Now what 
we are to remark is, how nature has prepared for 
the trials and severities of that season. These 
tender embryos are, in the first place, wrapped up 
with a compactness which no art can imitate ; in 
which state they compose what we call the bud. 
This is not all. The bud itself is enclosed in 



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NATURAL THEOLOGY, 425 

flcules ; 'which scales are foriBed from the remams 
cf past leaves^ and the rudiments of future ones ^^\ 
Neither is this the whole. In the coldest cli^ 
matesj a thard preservative is added^ by the bud 
having a coat of gum or resin, which, being co^B:- 
gealed, resists the strcHigest frosts. On the ap- 
proach of warm weather^ this gum is softened 
and ceases to be &n hindrance to the expam^Gm 
ef the leaves and flowers. AU this care is part ^ 
tfaat system of provisions which has for its object 
and consummation the production and perfecting 
of the seeds. 

The SEEDS th^nselves are packed up in a cap- 
inte, a vessel composed of ooats^ which^ compared 
with the rest of the flower, are strong and ioiigh. 

^^ This m not exacdy true. Buds are not endosed in 
scales fcHioed from the remains of past l^veB» except in 
a iew rare instances^ to which it cannoft be supposed 
thst the SAtbor refers; neither are they protected by what 
can correctly be called the rudiments of future leaves, 
or ore only protected in part. The extensive scales 
of a bud« those in which the office of protection more 
especially resides, are rudimentary leaves, which are 
formed at the end of the season, when the force of de- 
velopment in the vegetable system is weak and im- 
perfect; they do not become leaves another season, but 
are simply thrown off by the eaqmnsion of the leaves 
winch unlbld fWon 'wilhm them, 

u2 



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436 NATURAL THEOLOGY. 

From this vessel projects a tube, througli which 
tube the farina> or some subtile fecundating efflu- 
vium that issues from it, is admitted to the seed. 
And here also occurs a mechanical variety, ac- 
commodated to the different circumstances under 
which the same purpose is to be accomphshed. 
In flowers which are erect, the pistil is shorter 
than the stamina; and the pollen, shed from the 
antherae into the cup of the flower, is caught in 
its descent by the head of the pistil, called the 
stigma. But how is this managed when the 
flowers hang down (as does the crown-imperial 
for instance), and in which position, the farina, in 
its fall, would be carried from the stigma, and not 
towards it? The relative length of the parts ig 
now inverted. The pistil in these flowers is 
usually longer, instead of shorter, than the sta- 
mina, that its protruding summit may receive the 
pollen as it drops to the ground. In some cases 
(as in the nigella), where the shafts of the pistils 
or stiles are disproportionably long, they bend 
down their extremities upon the antherae, that 
the necessary approximation may be effected. 

But (to pursue this great work in its progress), 
the impregnation, to which all this machinery re- 
lates, being completed, the other parts of the 
flower fade and drop off, whilst the gravid seed- 
vessel, on the contrary, proceeds to increase its 



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NATURAL THEOLOGY. 437 

bulk, always to a great, and, in some species (in 
the gourd, for example, and melon), to a sur- 
prising comparative size; assuming in difiTerent 
plants an incalculable variety of forms, but all 
evidently conducing to the security of the seed. 
By virtue of this process, so necessary, but so 
diversified, we have the seed at length, in stone- 
fruits and nuts, incased in a strong shell, the shell 
itself enclosed in a pulp or husk, by which the 
seed within is, or hath been, fed ; or, more gene- 
rally (as in grapes, oranges, and the numerous 
kinds of berries), plunged overhead in a glutin- 
ous syrup, contained within a skin or bladder : at 
other times (as in apples and pears) embedded 
in the heart of a firm fleshy substance; or (as 
in strawberries) pricked into the surface of a soft 
pulp. 

These and many more varieties exist in what 
we coll fruits*. In pulse, and grain, and grasses; 

* From the conformation of fruits alone, one might be led, even 
without experience, to suppose, that part of this provision was 
destined for the utilities of animals. As limited to the plant, the 
provision itself seems to go beyond its object. The flesh. of an 
apple, the pulp of an orange, the meat of a plum, the fatness of 
the olive, ajipear to be more than sufficient for the nourishin*; of 
the seed or kernel. The event shows that this redundancy, if it 
be one, ministers to the support and gratification of animal 
natures ; and when we observe a provision to be more than suffi- 
cient for one purpose, yet wanted for another purpose, it is not 
unfair to conclude that both purposes were contemplated together. 
It favours this view of the subject to remark, that fruits are not 



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438 NATURAL THEOLOGY. 

in trees, and skrubs, and iowen ; the Tariety of 
the seed-vessels is incomputable. We have Hie 
seeds (as in the x>ea tribe) regnlarly disposed in 
parchment pods, which, though soft and men- 
branous, compktely exclude the wet even in flie 
heaviest rains; the pod ako, not seldom (as in 
the bean), lined with a fine down ; at other times 
(as in the senna) distended like a blown bladder: 
or we have the seed envdoped in wool (as in the 
cotton-plant), lodged (as in pines) between the 
hard and compact scales of a cone, or barricadoed 
(as in the artichoke and thistle) with spikes and 

(which th«y might have been) ready altogeUier, but that they 
ripen in succession throughout a g^eat part of the year; some 
in simmier; some in autumn ; that some require the slew 
naturation of the winter, and supply the spring ; also that Ham 
coldest firuits gprow in the hottest places. Cucumbers, pine-apples, 
melons, are the natural produce of warm climates, and contribat« 
-greatly, by their coolness^ to the refreehment of the inhalntaolB of 
those countries. 

I will add to this note the following observation cornmnnicated 
^o me by Mr. Brinkley. 

<< The eatable part of th« cherry or peadi iintt serves the pur- 
'peses of perfecting the seed or k^nel, by means of vessels paM- 
iffig through the stone, and which are veiy visible in a peadi- 
•tene. After the kernel it perfected, te stone becomes hard, 
and the vess^ cease their functions. Bvt the substance 8uv> 
rounding the stone is not then thrown awi^ as nselesa. That which 
was before only an iB sUu me ut tat perfecting 1^ fcern^ now 
receives and retains to itself the whole of the son's infiuenoe, 
and thereby becomes a grateful food to man. Also what an 
evident mark of design is the stone protecting the kernel I The 
iaterventien e€ the stene prevents the second use from iaterfiariog 
wHh the erst"— AW €ftke Jufhttr. 



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NATURAL THEOLOGY. 439 

prickles; in mnslirooms, placed imder a pent^ 
house ; in £enis, within slits in the back part of 
the leaf: oar (which is the most general organi- 
sation of all) we find them covered by strong:, 
dose tunides^ and attached to the stem accord- 
ing to an order appropriated to each plant, as 
is seen in the several kinds of grains and of 



In which ennmeration, what we have first to 
notice is, nnity of purpose under variety of ex- 
pedients. Nothing can be more single than the 
design ; more diversified than the means. Pel- 
licles, shells, pulps, pods, husks, skin, scales 
armed with thorns, are all employed in prosecut- 
ing the same intention. Secondly ; we may ob- 
serve, that;, in all these cases, the purpose is ful- 
filled within- a just and limited degree. We can 
peroehre, that if the seeds of plants were more 
strongly guarded than they are, their greater 
security would interfere with other uses. Many 
species of animals would suffer, and many perish, 
if they could not obtain access to them. The 
{dant would overrun the soil; or the seed be 
wasted fcwr want of room to sow itself. It is some- 
times as necessary to dei^oy particular species of 
plants, as it is, at other times, to encomrage their 
growth. Here, as in many cases, a balance is to 
be maintained between opposite uses. The pro- 



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440 NATURAL THEOLOOT. 

visions for the preservation of seeds appear to be 
directed chiefly against the inconstancy of the 
elements, or the sweeping destruction of incle- 
ment seasons. The depredation of animals, and 
the injuries of accidental violence, are allowed for 
in the abundance of the increase. The result is, 
that out of the many thousand different plants 
which cover the earth, not a single species, per- 
haps, has been lost since the creation. 

When nature has perfected her seeds, her next 
care is to disperse them. The seed cannot answer 
its purpose, while it remains confined in the cap- 
sule. After the seeds therefore are ripened, the pe- 
ricarpium opens to let them out ; and the opening 
is not like an accidental bursting, but, for the 
most part, is according to a certain rule in each 
plant. What I have always thought very ex- 
traordinary, nuts and shells, which we can hardly 
crack with our teeth, divide and make way for 
the little tender sprout which proceeds from the 
kernel. Handling the nut, I could hardly con- 
ceive how the plantule was ever to get out of it. 
There are cases, it is said, in which the seed- 
vessel, by an elastic jerk, at the moment of its 
explosion, casts the seeds to a distance. We all 
however know, that many seeds (those of most 
composite flowers, as of the thistle, dandelion, &c.) 
are endowed with what are not improperly called 



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NATURAL THEOLOGY. 441 

wings ; that is, downy appendages, by which they 
are enabled to float in the air, and are carried, 
oftentimes by the wind to great distances from 
the plant which produces them. It is the swell- 
ing also of this downy tuft within the seed-vessel 
that seems to overcome the resistance of its coats^ 
and to open a passage for the seed to escape. 

But the constitution of seeds is still more ad- 
mirable than either their preservation or their dis- 
persion. In the body of the seed of every species 
of plant, or nearly of every one, provision is made 
for two grand purposes: first, for the safety of 
the germ; secondly, for the temporary support 
of the future plant. The sprout, as folded up in 
the seed, is delicate and brittle beyond any other 
substance. It cannot be touched without being 
broken. Yet, in beans, peas, grass-seeds, grain, 
fruits, it is so fenced on all sides, so shut up and 
protected, that, whilst the seed itself is rudely 
handled, tossed into sacks, shovelled into heaps, 
the sacred particle, the miniature plaiit, remains 
unhurt. It is wonderful how long many kinds 
of seeds, by the help of their integuments, and 
perhaps of their oils, stapd out against decay. 
A grain of mustard-seed has been known to 
lie in the earth for a hundred years; and, as 
soon as it had acquired a favourable situation, to 
shoot as vigorously as if just gathered from the 

u5 



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442 NATVUAL TBBOLOOT. 

plmt Then, as to die second point, the ten- 
ponnrj support of tlie futuie plant, the natter 
•taasds thus. In grain, and pvlse, and kemda, 
and pippins, the germ eorapeses a verj small 
pMTt of the seed. The lest eensints of a noirir 
lioiia substance, frvm whidi the flpRmt dnnrE its 
aliment for some eonsidemble iiae after it is pot 
farth; viz^ until the fibres, shot out from the 
edier end of the seed, are able to imbibe jnioea 
fipom the earth, in a sufficient quantity fer ila 
dfemand. It is owing to this eonstitntiai^ thi^ 
we see seeds sprout, and the sprouts make a ceo- 
siderable progress, without anj earth at alL It 
is an economy, alae, in which we remark a dose 
analagy between the seeds of plants and the eggs 
of animals. The same point is provided for, in 
tibe same manner, in both. In the egg, the resir 
dence of the lavii^ principle, the cicatrix, fomn 
a very minute part of the contents. The wlnte 
and the white mily is expended in the formatisn 
af the chicken. The yolk, very Httle altered or 
diminished, is wiaj^ped up in the abdomen <^ the 
jKmng bird, when it quks the shdl; and serves 
for its nourishment, till it have learnt to pick its 
own food. This perfectly resembles the first 
afutrition of a plant. In the plant, as well as in 
the animal, the stnuinre has every diaracter of 
eontrivaiKe bdangittg to it: in both it bcmfa 



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NATURAL THEOLOGY. 443 

the trflnsition fircm prepacied to iiiiprepax>ed ali- 
ment; in both, it is prospective and compen- 
satory. In animals which snek, this intermediate 
nourishment is suj^lied by a different source. 

In all subjects^ the most common observations 
are the best, when it is their truth and strength 
which have made them common. There are, of 
this sort, two coaceming plants, which it £alk 
within our j^bm to notice. The first relates tx>, 
what has already been toudied upon^ their get- 
mmation. When a gram of com is cast into the 
l^rcmnd, this is the change whidi takes ptace. 
From one end of the grain issues a green ^rout^ 
fifon the other, a number of wbste fibrous threads. 
How can this be e3EpJiained? Why not s!{nrouts 
trom both ends? why not fibrous threads firom 
both ends? To what is the difierence to hb 
referred, but to design; to the different uses 
whidi the parts are thereafker to serve; uses 
wUeh discover ihemsdves in the sequel of the 
process ? The sprout, or phunule, struggles into 
the air ; and becomes the plant, of whk^ Gcem 
the first, it contained Ihe rudiments : the fibres 
shoot into the earth; and thereby both fix the 
plattt to the ground^ and collect no\arishme»t 
ftom the s<m1 for its s!i;q>port. Now, what is not a 
little remarkable, the parts issuing firom the seed 
take their xespociiife direetioiuii, into whatever 



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444 NATURAL TH£OLOGY. 

position the seed itself happens to be cast. If 
the seed be thrown into the wrongest possiUe 
position ; that is^ if the ends point in the ground 
the reverse of what they ought to do, every thing, 
nevertheless, goes on right The sprout, after 
being pushed down a little way, makes a bend« 
and turns upwards ; the fibres, on the contrary, 
after shooting at first upwards, turn down. Of 
this extraordinary vegetable fact, an account has 
lately been attempted to be given. " The plu- 
mule (it is said) is stimulated by the air into 
action, and elongates itself when it is thus most 
excited; the radicle is stimulated by moisture, 
and elongates itself when it is thus most excited. 
Whence one of these grows upward in quest of 
its adapted object, and the other downward*." 
Were this account better verified by experiment 
than it is, it only shifts the contrivance. It does 
not disprove the contrivance; it only removes it a 
little farther back. Who, to use our author s 
own language, '' adapted the objects?" Who 
gave such a quality to these connate parts, as to 
be susceptible of different '' stimulation ; " as to 
be ''excited" each only by its own element, and 
precisely by that which the success of the vege- 
tation requires ? I say, '' which the success of the 

♦ Darwin's Phytologia, p. 144, 



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NATURAL THEOLOGY. 445 

vegetation requires:" for the toil of the husband- 
man would have been in vain, his laborious and 
expensive preparation of the ground in vain ; if 
the event must, after all, depend upon the posi- 
tion in which the scattered seed was sown. Not 
one seed out of a hundred would fall in a right 
direction. 

Our second observation is upon a general pro- 
perty of climbing plants, which is strictly mecha- 
nical. In these plants, from each knot or joint, 
or, as botanists call it, axilla, of the plant, issue, 
close to each other, two shoots, one bearing the 
flower and fruit, the other drawn out into a wire, 
a long, tapering, spiral tendril, that twists itself 
round anything which lies within its reach. Con- 
sidering that in this class two purposes are to be 
provided for (and together), fructification and 
support, the finiitage of the plant and the susten- 
tation of the stalk, what means could be used 
more eflFectual, or, as I have said, more mechanical, 
than what this structure presents to our eyes? 
Why, or how, without a view to this double 
pui'pose, do two shoots, of such different and ap- 
propriate forms, spring from the same joint, from 
contiguous points of the same stalk ? It never 
happens thus in robust plants, or in trees. " We 
see not," says Ray, '^ so much as one tree, or 
shrub, or herb, that hath a firm and strong stem. 



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446 NATURAL TBC0M6T. 

and <lu^ is aUe to movnt up asd stand aknie 
without assistance, fwrnkhed with Ac9e trndriisJ^ 
Make only so simple a conpanson as tliat be- 
tween a pea and a bean. Wh j does the pea pot 
forth tendrils, tlie beam Bot? but becaose die stalk 
of the pea cannot support itself, the stalk of tibie 
bean can. We may add also^ as a circnmstaaoe 
not to be orerlooked, that, in the pea tribe, ihese 
clasps do Bot make their appearance tiU they are 
wanted — iSH the plant has grown to a height to 
stand in need of support. 

This word ^ support" suggests to nsarefleetianL 
vpon a property of grasses, of com, and cbxxa. 
The faoBow «tems of these classes of ^ants ase 
set at certain intanrak with joints. These joials 
are not foimd in Hat trunks of tvees, or in the 
soHd stalks of plants* There may be oth» uses 
of these joii^ ; but the fact is, and i4 fq)pears to 
be at least one purpose designed by them, that 
they corretorafe the stem, which by its length and 
hoUowness would otherwise be too liable to break 
or bend. 

Grosser are Nature's care. With these she 
dothes the earth — with these she sustains its in- 
hal»tants. Cattle feed upon their leaves — birds 
iqpon their smaller seeds — ^m^i up<»ft the larger; 
lor few readers need be told that the plants which 
produce onr faeead 0(»cn belong to this dass. In 



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NATURAL THBOT.OGT. 447 

tikove tribes vMdi are more generally considered 
ftg grasses, their extcaordmary roenna niid peters 
vi prcserrattoii and in^ease, ihek kardiness, thek 
aftmost nnconqii^nible dispositioii to qp>pead> their 
facakies of revirisoeiice^ coimdde with the int^i- 
tkm ot Nature eonoemmg them. They thrive 
under a treatment by which other plants are de- 
stroyed. The more their k»res are consvmed, 
the more their roots increase. The more they 
ave trampled upon^ the thicker they grow. Many 
of the seemingly dry and dead leaves of grasses 
revive, and renew their verdare in the spring"*. 
bi krfty mountaans, where the sunmier heats are 
not su£^ent to ripen the seeds, grasses abound 
wUdb are viviparous, and ccnseqfientiy able to 
poropagate th^ouB^ves wi^ont seed. It is an eb- 
servation likewise which has often been made, 
that herbivorcus animals attach themselves to the 
loaves of grasses, and if at Uberty in theirpastmres 
io range and choose, leave nntonched the straws 
wUA support the flowers'*'* 

^ Here, to be correct, we should read ** Many grasses 
whose leaves are so dry and withered that the plants 
appear dead, revive and renew their existence m the 
spring by pusUng fcntk new leaves fnjm the bosom 
af the former ones*" 

* WfthenngrBoi Anr.Toi i p. 18, ed. 2nd. 



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448 NATURAL THBOLOGT. 

The GENERAL properties of vegetable nature, or 
properties common to large portions of that king*- 
dom, are almost all which the compass of our 
argument allows us to bring forward. It is im- 
possible to follow plants into their several species. 
We may be allowed, however, to single out three 
or four of these species as worthy of a particular 
notice, either by some singular mechanism, or by 
some pecuHar provision, or by both. 

I. In Dr. Darwin's Botanic Garden (I. 395, 
note) is the following account of the vallisneria, 
as it has been observed in the river Bhone : — 
" They have roots at the bottom of the Bhone. 
The flowers of the female plant float on the sur- 
face of the water, and are furnished with an elastic 
spiral stalk, which extends or contracts as the 
water rises or falls — this rise or fail, from the tor- 
rents which flow into the river, often amounting to 
many feet in a few hours. The flowers of the 
male plant are produced under water ; and as soon 
as the fecundating farina is mature, they separate 
themselves from the plant, rise to the surface, and 
are wafted by the air, or borne by the currents, to 
the female flowers." Our attention in this nar- 
rative will be directed to two particulars : first, to 
the mechanism, the " elastic spiral stalk," which 
lengthens or contracts itself according as the 
water rises or falls; secondly, to the provision 



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NATURAL THEOLOGY. 449 

which is made for bringing the male flower, which 
is produced under water, to the female flower, 
which floats upon the surface. 

II. My second example I take from Withering s 
Arrangement, vol. ii. p. 209, ed. 3. '' The cuscuta 
furopcea is a parasitical plant. The seed opens. 




and puts forth a little spiral body, which does not 
seek the earth to take root, but climbs in a spiral 
direction, from right to left, up other plants, from 
which, by means of vessels, it draws its nourish- 
ment." The "little spiral body" proceeding from 
the seed is to be compared with the fibres which 
seeds send out in ordinary cases ; and the compa- 
rison ought to regard both the form of the threads 
and the direction. They are straight; this is 
spiral. They shoot downwards; this points up- 



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450 NATVEAL TBBOUXIT. 

wudi. In tlie rule and in the exception we 
eqnallj perceive design^. 

*®^ Thia statement is incorrect^ When the seed of 
cuscuta opens, it puts forth a little thread-shaped body, 
namely, a young root, which, as in other plants, plunges 
into the earth, and from the opposite end elevates a 
young and slender stem. The latter, after a little while, 
applies itself to some neighbouring plant, and emits very 
short broad suckers on the side of its stem, which is 
placed in contact with the other plant; by these suckers 
it fastens itself upon the new branch, round which it 
twines, and as soon as it is secure in its new station its 
root perishes, and it ceases to have any communication 
with the earth. This property in the cuscuta seems to 
be given it in consequence of its root not having the 
power that suck parts usually possess of branching, 
lengthening, and attracting nutriment from the earth. 
If the cuscuta seed germinates at a distance from any 
living branch to which it can adhere, it elevates its 
stem for a short time in the air and then dies. If it is 
so placed as to be able to come in contact only with 
dead branches, still it dies ; and it is only when it suc- 
ceeds in fixing itself upon a living branch that it emits 
its suckers and continues to exist. Once attached to 
the living stem of another plant, it takes that for its 
base, and turning round once or twice, then darts forth 
ill a straight line, touches something else which it also 
fixes in its folds, and thus travels ^om plant to plant, 
sometimes covering a very considerable extent of bushes. 



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NATURAL TIM0L06Y. 451 

III. A better known pftrs^ieal pbmi is Ae 
evergreen shrub, called the missfdioe. What wc 
liave to remark in it is a singular instaifeee of 
compensation. No art hath yet made these plants 
take root in the earth. Here, therefore, might 
seem to be a mortal defect in their constitution. 
Let us examine how this defect is made up to 
them. The seeds are endued with an adhesive 
quality so tenacious, that, if they be rubbed upon 
the smooth bark of almost any tree, they will 
stick to it. And then what follows? Roots, 
springing from these seeds, insinuate their fibres 
into the woody substance of the tree ; and the 
event is, that a misseltoe plant is produced next 
winter*. Of no other plant do the roots refiise 
to shoot in the ground ; of no other plant do the 
seeds possess tliis adhesive, generative quality, 
when applied to the bark of trees ^°*. 

IV. Another instance of the compensatory sys- 
tem is in the autiunnal crocus, oar meadow saffron 
(colchicwm autumnale). I have pitied this poor 
plant a thousand times. Its bbssom rises (mt 
of the ground in the most forlorn ccmdition pos- 

"" These stat^nents are true, not only of the inieseltoe 
or viscum actum, but of the whole natural order Loran- 
ikaece^ with one exception. 

* WUhering, Bot Arr. vol* i. p. ^S, cd. 2ad. 



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452 ^ATURAL THEOLOGY. 

aible ; without a sheath, a fence, a calyx, or even 
a leaf to protect it : and that, not in the spring 
not to be visited by summer suns, but under all 
the disadvantages of the declining year. When 




we come, however, to look more closely into the 
structure of this plant, we find that, instead of 
its being neglected. Nature has gone out of her 
course to provide for its security, and to make 
up to it for all its defects. The seed-vessel, 
which in other plants is situated within the cup 
of the flower, or just beneath it, in this plant Ues 
buried ten or twelve inches underground within 
the bulbous root. The tube of the flower, which 
is seldom more than a few tenths of an inch long, 
in this plant extends down to the root. The 
styles in all cases reach the seed-vessel; but it is 



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NATURAL THEOLOGY. 453 

in this by an elongation unknown to any other 
plant. All these singularities contribute to one 
end. " As this plant blossoms late in the year, 
and probably would not have time to ripen its 
seeds before the access of winter, which would 
destroy them. Providence has contrived its struc- 
ture such, that this important ofSce may be per- 
formed at a depth in the earth out of reach of 
the usual effects of frost*." That is to say, in 
the autumn nothing is done above ground but 
the business of impregnation ; which is an affair 
between the antherse and the stigmata, and is 
probably soon over. The maturation of the im- 
pregnated seed, which in other plants proceeds 
within a capsule, exposed together with the rest 
of the flower to the open air, is here carried on, 
and during the whole winter, within the heart, 
as we may say, of the earth, that is, '^ out of the 
reach of the usual effects of frost." But then a 
new difficulty presents itself. Seeds, though 
perfected, are known not to vegetate at this 
depth in the earth. Our seeds, therefore, though 
so safely lodged, would, after all, be lost to the 
purpose for which all seeds are intended. Lest 
tins should be the case, ^^a second admirable 
provision is made to raise them above the sur- 

* Withering, ubi supra, p. 360. 



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454 NATUIUO* TUBOLOOT. 

<«oe vrhen tficy we perfected^ and to sow them 
«l a proper distaace :" yiz., the germ grows Mf 
aft the wpring, upon a firuit-Btalk, accompamed 
with kaves. The soedB now^ in oonnwii witfa 
those of other plants, have the hemefit of the 
snnuner, and are sown npotn the aiir£Eice. The 
order of vegetation externally is this; — the phnt 
produces its flowers in September; its leaves aotd 
fruits in the spring following. 

V. I gire the account of tbe diatuea Bncsctpala, 
an extraordinary American plant, as some late 
authors have rdated it : but whether we be yet 
enough acquainted with the plant, to bring every 
part of this account to the test of repeated and 
fiuwiltar observation, I am unable to say. ^Ite 
kaves are jointed, and inmished wiih two rowi 
ci fltroBg prickles ; their surfSwes oDvcsed with a 
mnnber of minttte glands, which secrete a sweet 
hqoor that aQinei the approach of flies. When 
these parts are tonched by the legs of ffiea. 
the two lobes of the leaf instantiy spring np» 
tbe rows of prickles lock themselves tsai, to- 
geth^, and sqiueeze die unwary mumal to death V 
Here, under a new model, we recognise the 
anci^it plan of nature, via., the relation of parts 
and provisions to one another:, iD a common 
oflSce, and to the utility of the organized body 

*^SmeHie'ff PhiU of Kat. Hist. yol. i. p. 5. 



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NATURAL THEOLOGY. 



455 



to whidi they belong. The attracting' syrup "*, 
Ae rows of strong prickles, their position so as 
to interlock the joints of the leaves ; and, what is 
more than the rest, that singular irritability of 
their surfaces, by which they close at a touch; 
all bear a contributory part in producing an 
efiTect, connected either with the defence or with 
the nutrition of the plant ^^^. 

^^ From this account must be omitted what is said of 
the syrup that allures the approach of flies. There'is 
no such attraction upon the leaves of the dioncea. 

"" The pitcher-plant, nepenthes distillatoriay of the 




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456 NATURAL THEOLOGY. 

Eaity 18 another example which may be given. It 
grows natural pitchers or tankards, holding from a pint 
to a qoart of pure water. Even when raised in this 
country under glass, they have been known to hold 
half-a-pint. The plate represents these, with their lids 
AA, which move on hinges, opening in moist weather, 
and shutting quite close in dry to prevent evaporation. 
When the pitcher becomes full, and requires additional 
support, the hook A behind the lid seizes on some 
neighbouring tendril, and holds by it. BB are young 
pitchers just unfolding. This water which supplies the 
pi'chers is secreted by the process of vegetation, and is 
perfectly pure, though the plant grows in a muddy and 
unwholesome marsh. 

The palo de vaca^ or cow-tree of South America, 
yields a delicious and nutritive milk on its trunk being 
pierced ; and it grows in the most parched soil, and in 
a climate where rain is unknown during half the year. 

The supply of fine water afforded by the tillandsia, 
or water-with, in Jamaica, and by the bejuco, or cissus 
laiifolia in the East, on cutting, is a feet of the same 
class. The latter plant also twines round other trees, 
and affords, as it were, a reservoir for their use. 



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